Glossary – Page 9 – The Diamond Certification Laboratory of Australia (DCLA)

July, 2017February, 2025

Hot Laser Inscription

Advanced Technology for Diamond Identification and Customisation
Hot laser inscription refers to the process of using a high-powered laser beam to inscribe a number, unique identifier, or custom personal message onto the girdle of a diamond. The girdle is the outermost edge of the diamond, and it provides a subtle location for these inscriptions without interfering with the overall visual appeal of the stone. Hot laser inscription is often used for diamond identification, tracking, and personalisation, offering a way to ensure a diamond’s authenticity and ownership.

How Hot Laser Inscription Works
Hot laser machines use a laser beam that operates at a higher wavelength compared to cold lasers, allowing the beam to penetrate deeper into the diamond’s structure. During the inscription process, the laser creates a mark by vaporising small areas of the surface, leaving a permanent, microscopic engraving.

Key Characteristics of Hot Laser Inscription:
High Wavelength Laser – The hot laser operates at a higher wavelength, which allows it to penetrate the surface of the diamond and engrave more durable markings into the material. This is different from cold laser inscription, which uses lower-energy lasers that do not penetrate as deeply into the diamond.
Engraving Depth – The heat from the laser allows the inscription to go deeper into the diamond than cold laser inscription, potentially affecting the integrity of the stone if done improperly.
Customisation – This process can be used to engrave custom numbers, letters, logos, or even personal messages onto the girdle of the diamond, allowing for a unique and personalised touch.
Risks of Hot Laser Inscription
While hot laser inscription provides a more permanent engraving than cold laser techniques, it also carries certain risks due to the depth of penetration. The intense heat used by the laser can sometimes result in the formation of microscopic cracks, chips, or even fractures in the diamond if not executed with precision and care.

Potential Risks Include:
Damage to the Diamond – The high-powered laser beam can potentially cause thermal damage to the diamond, leading to the formation of internal fractures or chips on the surface, especially if the inscription is too deep or improperly aligned.
Structural Weakness – Engraving can affect the structural integrity of the diamond, particularly if the laser beam is used too aggressively. This is more likely with diamonds that have inherent flaws or inclusions, as the laser can exacerbate weaknesses in the stone.
Visible Damage – If the engraving is not done carefully, it may leave visible damage on the girdle or even affect the diamond’s overall appearance when viewed closely.
Hot Laser Inscription vs. Cold Laser Inscription
While both hot and cold laser inscription methods offer a way to personalise and authenticate a diamond, there are notable differences between the two techniques in terms of technology and potential impact on the diamond.

Hot Laser Inscription:
Penetration Depth – Hot lasers can penetrate deeper into the diamond, allowing for more permanent engravings.
Potential Damage – The higher wavelength and intense heat used in hot laser inscription can sometimes result in structural damage to the diamond, such as chips or fractures.
Uses – Best for marking diamonds with custom messages, serial numbers, or for authentication purposes.
Cold Laser Inscription:
Shallow Penetration – Cold lasers operate at a lower wavelength, which means they leave a surface-level engraving without significantly affecting the diamond’s structure.
Less Risk of Damage – Cold laser inscriptions are less likely to cause damage to the diamond, as they do not penetrate as deeply into the material.
Uses – Ideal for surface engraving for identification, such as serial numbers or small logos, without compromising the diamond’s integrity.
Common Uses of Hot Laser Inscription
Hot laser inscription is commonly employed for several practical and sentimental purposes in the diamond industry, particularly for authentication, tracking, and personalisation.

1. Identification and Authentication:
Unique Serial Numbers – Diamonds often receive a serial number that matches the number on their grading certificate. This allows for easy identification and tracking, helping to prevent fraud and theft.
Verification of Authenticity – The inscription can serve as a verification tool to ensure the diamond is genuine and has not been swapped or substituted for a counterfeit stone. This is especially important for diamonds sold with a graded certificate from a laboratory such as GIA, DCLA, or others.
2. Personalisation and Sentimental Engraving:
Custom Messages – Many people choose to have a personalised message engraved on the diamond’s girdle, such as an anniversary date, initials, or a meaningful quote. This adds a sentimental touch to the diamond, making it even more special.
Gifting and Commemoration – Hot laser inscription is also commonly used to mark significant milestones, such as engagements, weddings, or other special occasions, making the diamond even more unique and memorable.
3. Tracking and Security:
Diamond Inventory – For jewellers or collectors, hot laser inscription is an excellent way to track inventory or ensure that the diamond in question is easily identifiable if needed for security or insurance purposes.
Anti-Theft Measure – Engraving a unique identification number or marking on a diamond can help ensure that stolen diamonds can be traced back to their rightful owner, making them harder to sell or resell.
Benefits of Hot Laser Inscription
Despite the potential risks of penetration and damage, hot laser inscription offers several benefits that make it a popular choice in the diamond industry:

1. Permanent and Visible Identification:
Hot laser inscriptions are permanent and cannot be easily removed, making them an excellent tool for authentication and identification. This is crucial in protecting the diamond from theft or fraud.
2. Customisation:
The ability to engrave personal messages, dates, or other custom marks makes hot laser inscription a unique way to add a personal touch to a diamond, especially in engagement rings or family heirlooms.
3. Increased Security:
The unique markings provided by hot laser inscription serve as an effective deterrent against theft and unauthorised sales, as the engraving acts as a visual signature that is difficult to duplicate or alter.
Considerations Before Using Hot Laser Inscription
While hot laser inscription offers many advantages, it is essential to consider potential risks before proceeding with this engraving method. For diamonds with existing flaws or those of lower quality, hot laser inscription might not be advisable, as it could worsen internal damage. Additionally, it is crucial to ensure that the inscription is done by a skilled and reputable professional to avoid mistakes and damage.

Things to Consider:
Diamond Quality – Hot laser inscription may not be ideal for diamonds with visible inclusions or existing fractures, as it could exacerbate these flaws.
Professional Inscription – Always have hot laser inscription performed by a skilled professional to ensure the laser is used correctly and the diamond is not damaged.
Increased Value for Identification – For high-value diamonds or those with certificates from recognised grading laboratories, the added identification value may outweigh the risks of inscription.

July, 2017February, 2025

HPHT (High Pressure High Temperature) Treatment

Enhancing the Colour of Diamonds
HPHT treatment refers to a method used to alter or enhance the colour of diamonds through the application of extreme high pressure and high temperature conditions in a laboratory setting. This process mimics the natural conditions that diamonds undergo deep within the Earth, where extreme heat and pressure transform carbon atoms into diamond structures. By replicating these conditions artificially, HPHT treatment enables the alteration of a diamond’s colour and sometimes improves its clarity.

How HPHT Treatment Works
The HPHT treatment process involves subjecting a diamond to high pressure (often exceeding 5 gigapascals) and high temperature (around 1,300°C to 1,600°C) inside a specially designed machine. These conditions force the diamond’s atomic structure to rearrange, causing specific colour changes or enhancing existing characteristics.

The Process:
Diamond Placement – A diamond is placed inside a specially designed HPHT press. This machine applies extreme pressure and temperature to the diamond, which triggers changes in its molecular structure.

Heat and Pressure Application – The diamond is exposed to high heat and pressure conditions, often with the addition of specific gaseous environments (e.g., hydrogen or nitrogen) to encourage particular colour changes.

Molecular Rearrangement – Under the extreme conditions, the diamond’s carbon atoms rearrange to form a new, altered atomic structure. This can result in a noticeable shift in the diamond’s colour.

Cooling and Final Inspection – After the treatment, the diamond is slowly cooled and carefully inspected. The result is a diamond with a modified colour profile, often exhibiting more vibrant, consistent hues.

What Changes Can HPHT Treatment Cause?
HPHT treatment is most commonly used to enhance or alter the colour of diamonds. It is especially effective in diamonds with certain characteristics that make them more suitable for colour enhancement. The main colours that can be affected by HPHT treatment include:

1. Colour Enhancement:
Yellow to Fancy Yellow or Fancy Intense Yellow – Some diamonds with a yellowish tint can be treated to enhance their yellow hue, resulting in a more vibrant and noticeable fancy yellow or fancy intense yellow.
Brown to Near-Colourless or Fancy Colours – Brown diamonds, which naturally have a lower value due to their colour, can be treated to remove their brownish hues and transform them into more desirable colours, such as near-colourless or even fancy pinks, blues, or greens.
Enhancing Existing Colours – Diamonds with a faint yellow, brown, or grey hue can be treated to intensify their natural colour, making the diamond more vibrant and valuable.
2. Colour Modifications:
Permanent Colour Changes – HPHT treatment can also be used to permanently modify the natural colour of a diamond. For example, a diamond that is initially a dull yellow may be treated to become a more saturated fancy yellow or even a fancy vivid colour.
Disguising Minor Imperfections – In some cases, HPHT can help reduce the appearance of minor inclusions or discolouration within the diamond, resulting in a more visually appealing stone.
Diamonds Suitable for HPHT Treatment
Not all diamonds are suitable for HPHT treatment, and the process works best on diamonds that exhibit certain characteristics:

Type IIa Diamonds – These diamonds are typically more receptive to HPHT treatment. Type IIa diamonds, which are nearly pure carbon, often lack nitrogen impurities and are the ideal candidates for colour enhancement.
Browns, Yellows, and Greens – While HPHT can be used to alter a variety of colours, it is most effective on brown, yellow, and green diamonds. These diamonds can be enhanced to display a more desirable or intense colour.
However, diamonds that already possess a rich natural colour or have significant inclusions may not benefit from HPHT treatment, as the process might not improve the stone’s appearance or could even degrade its value.

Common Uses of HPHT Treatment
The HPHT process is typically employed for diamonds that are not of the highest colour grade or for those that exhibit certain characteristics that would otherwise lower their value. By using HPHT, diamonds can be transformed into more aesthetically pleasing stones that may fetch higher market prices.

1. Colour Enhancement for Decorative or Investment Purposes:
Fancy Coloured Diamonds – Many fancy coloured diamonds, such as fancy yellow or fancy pink, are enhanced using HPHT treatment to make them more vibrant. The process can elevate a diamond from a low-grade stone to one that is more marketable, increasing its desirability.
2. Cost-Effective Enhancement:
Affordable Coloured Diamonds – HPHT treatment is often used to treat diamonds that may not have a high natural colour but possess potential for colour enhancement. This makes the diamonds more appealing to consumers who are seeking affordable coloured stones.
3. Reworking Lower-Quality Stones:
Transforming Brown Diamonds – Brown diamonds, which are generally considered less valuable, can be transformed into more attractive fancy colours through HPHT treatment, increasing their market value.
Benefits of HPHT Treatment
There are several key benefits of using HPHT treatment to enhance the colour of diamonds:

1. Improved Aesthetic Appeal:
Vibrant Colours – HPHT treatment enhances the natural colour of diamonds, making them more visually striking and desirable to consumers.
2. Cost-Effective Colour Enhancement:
Affordable Enhancement – HPHT offers a more cost-effective way to improve the colour of a diamond compared to other methods, such as irradiation or coating, while still offering permanent results.
3. Increased Market Value:
Higher Market Price – Treated diamonds with enhanced colours, especially those in the fancy colour range, often command higher prices than their untreated counterparts.
Considerations and Disclosure
While HPHT treatment can improve a diamond’s colour, it is important to consider the following:

1. Transparency in Treatment Disclosure:
Disclosure – It is essential that HPHT treatment is fully disclosed to the buyer when purchasing a diamond. Some consumers prefer untreated diamonds, especially if they are looking for a stone with natural colour and characteristics. Reputable sellers and grading laboratories such as GIA, IGI, and DCLA typically provide information on whether a diamond has undergone HPHT treatment.
2. Effect on Resale Value:
Resale Considerations – While HPHT-treated diamonds can be more attractive in terms of colour, it’s important to note that their resale value may differ from that of naturally coloured diamonds. Treated diamonds may not always fetch the same prices as their untreated counterparts, especially if the treatment is not properly disclosed or valued.

July, 2017February, 2025

Heart Cut

The Symbol of Love in Diamond Shape
The heart cut is one of the most romantic and symbolic diamond shapes, often chosen for engagement rings, pendants, and other special jewellery as it represents love and affection. It is a modified brilliant cut, which means that it is based on the traditional round brilliant cut, but with a distinct cleft at the top and a tapering point at the bottom, creating the unmistakable shape of a heart.

Features of the Heart Cut Diamond
The heart cut diamond is unique due to its distinctive heart shape, combining rounded and pointed elements in a single stone. This cut’s elegance and symbolism make it a popular choice for meaningful gifts and milestones.

Key Characteristics:
Cleft at the Top – The heart shape features a cleft or indentation at the top, which divides the diamond into two equal lobes, creating the upper, rounded parts of the heart.
Tapering Point – The bottom of the heart cut tapers into a sharp, pointed end, symbolising the arrow of Cupid or the pointed direction of love.
Balanced Proportions – The heart should maintain a balanced symmetry between the two lobes at the top and the pointed tip at the bottom to ensure the heart shape appears well-formed and even.
The Heart Cut Diamond: A Symbol of Love and Romance
The heart-shaped diamond is the ultimate symbol of romantic love, making it a popular choice for those seeking to commemorate a relationship. Its sentimental value is often just as important as its physical appearance. Whether it is used for an engagement ring or anniversary gift, the heart shape carries with it an undeniable sense of emotion and devotion.

Symbolism of the Heart Cut:
The heart shape represents eternal love and affection, making it one of the most meaningful choices for gifting.
The heart cut’s cleft and pointed end also evoke the imagery of Cupid’s arrow, a timeless symbol of love and passion.
Proportions and Symmetry in the Heart Cut Diamond
The shape and symmetry of a heart cut diamond are essential in determining its overall beauty and visual appeal. The heart shape is one of the more complex diamond cuts, requiring a high level of skill to ensure its proportions are perfect.

Key Proportions:
Symmetry of the Two Lobes – The two rounded lobes at the top of the heart should be even and symmetrical to each other, without any noticeable disparity in size. Any irregularity in the shape can make the heart appear uneven and distort its visual appeal.
Tapering Point – The pointed end should be sharp and centred, not too wide or too thin. A well-shaped heart cut will have a graceful taper that leads to a balanced and harmonious appearance.
Length-to-Width Ratio – The ideal length-to-width ratio for a heart cut diamond is typically between 1.00 and 1.05. This ensures that the heart looks balanced, neither too elongated nor too rounded.
Symmetry and Cut Quality
A high-quality heart cut diamond will be well-symmetrical, with both sides of the heart being mirror images of each other. Imperfect symmetry can make the heart look misaligned or even more like a rounded marquise rather than a true heart shape. Therefore, when evaluating a heart-shaped diamond, symmetry is one of the most important factors to consider.

Light Performance and Sparkle
Like other brilliant cuts, the heart-shaped diamond benefits from its facet arrangement, which helps it to reflect light brilliantly. The symmetry and quality of the cut significantly impact how well the diamond sparkles and how the facets interact with light.

Brilliance and Fire
A well-cut heart diamond will exhibit brilliance (white light reflection) and fire (the dispersion of coloured light). These qualities are enhanced by the facets of the diamond, which are strategically designed to maximise light reflection.
A poorly cut heart shape, however, can result in a dull appearance, with light not being properly reflected or dispersed.
Choosing a Heart Cut Diamond: Considerations
When selecting a heart-shaped diamond, it is crucial to consider factors such as cut quality, clarity, colour, and carat weight, all of which can impact the appearance of the stone.

1. Cut Quality
Cut quality is of the utmost importance for a heart-shaped diamond, as it dictates how well the stone will perform in terms of sparkle and symmetry. A well-cut heart will show excellent light performance and exhibit the clean, defined heart shape.
2. Clarity
Since the heart-shaped diamond has many facets, it can sometimes reveal inclusions and blemishes more clearly than other shapes. Therefore, it is recommended to choose a diamond with a higher clarity grade, such as VS1 or VS2, to ensure that any imperfections do not affect the diamond’s visual appeal.
3. Colour
The colour of a heart-shaped diamond should also be considered, as the cut of the stone can make any colour variations more noticeable. A diamond with a colour grade of G or above is ideal for achieving a bright, white appearance in the heart cut.
4. Carat Weight
The carat weight of a heart-shaped diamond will affect its overall size and visual impact. Since heart-shaped diamonds are often used in statement jewellery, choosing a larger carat weight can help the heart shape appear more prominent.
Setting a Heart Cut Diamond
The heart shape’s romantic appeal makes it a popular choice for engagement rings, pendants, and earrings. When selecting a setting for a heart cut diamond, the design should complement the symbolism and shape of the stone.

Engagement Rings
Solitaire settings allow the heart shape to be the focal point, drawing attention to the unique shape and romantic significance.
A halo setting can enhance the heart’s appearance by making it look larger and more dazzling, as the surrounding smaller diamonds create a stunning contrast.
Other Jewellery
The heart shape is often used in pendants, where the diamond can be the focal point of a delicate chain, or in earrings to create a cohesive set that represents love.

July, 2017February, 2025

Hearts & Arrows

A Symbol of Precision and Symmetry in Diamonds
The term Hearts & Arrows refers to a distinct and beautiful pattern that appears in some high-quality diamonds, primarily those with round brilliant cuts and, occasionally, square cushion cuts. This pattern is the result of exceptional symmetry and precision in the diamond’s cut, showcasing the alignment of the facets in such a way that a specific visual effect is created when the diamond is viewed from certain angles.

Understanding the Hearts & Arrows Pattern
When a diamond is perfectly cut with optimal symmetry, it can display the Hearts & Arrows pattern, which is best seen when the diamond is viewed under magnification. The pattern consists of eight arrowheads visible when viewed from above (through the crown) and eight heart shapes visible when viewed from below (through the pavilion).

Key Characteristics of Hearts & Arrows:
Eight Arrowheads – When viewed through the crown (the top portion of the diamond), the facets create a symmetrical pattern that appears as eight arrow-shaped figures. This configuration is due to the alignment of the table facet with the eight main facets surrounding it.
Eight Heart Shapes – When viewed through the pavilion (the bottom part of the diamond), the same alignment of facets produces eight heart-like shapes, arranged symmetrically around the centre. These shapes appear because of the reflection of the facets from the pavilion and the crown.
Perfect Symmetry – The creation of the Hearts & Arrows pattern is a result of a perfectly symmetrical diamond cut. The precision required to achieve this pattern is indicative of a high-quality diamond cut.
Hearts & Arrows and Diamond Cut Quality
While the Hearts & Arrows pattern is a hallmark of symmetry and precision, it does not necessarily indicate that the diamond is of the highest cut grade, such as an Ideal Cut. Instead, it simply means that the diamond has exceptional faceting and is well-aligned, which contributes to its overall visual appeal.

Cut Quality and Symmetry
Ideal Cut Diamonds often display the Hearts & Arrows pattern, though not every Ideal Cut will exhibit it. The pattern itself is a result of careful and meticulous cutting, with a focus on achieving perfect symmetry, which enhances both the brilliance and fire of the diamond.
Diamonds with the Hearts & Arrows pattern are often graded as having excellent symmetry but are not automatically classified as Ideal based solely on the appearance of the pattern.
Importance of Symmetry in the Hearts & Arrows Pattern
Symmetry is key to the Hearts & Arrows pattern’s formation. A diamond with this feature indicates that its facets have been cut in perfect alignment, which ensures optimal light performance.
While perfect symmetry enhances a diamond’s brilliance, it is important to remember that the Hearts & Arrows pattern itself does not affect the diamond’s overall colour or clarity.
How Hearts & Arrows Enhances the Diamond’s Appearance
The Hearts & Arrows pattern contributes to the diamond’s overall visual appeal by ensuring that the facets are aligned in such a way that they enhance the diamond’s brilliance and fire.

Brilliance and Fire
The alignment of facets in a diamond that exhibits Hearts & Arrows results in more efficient light reflection, increasing the brilliance of the diamond (the amount of white light returned).
The symmetry ensures that the diamond displays fire, or the dispersion of coloured light, as the light is reflected and refracted through the facets with greater consistency. This enhanced light performance contributes to the diamond’s ability to sparkle in any lighting condition.
Visual Perception
Diamonds that display Hearts & Arrows often appear more radiant and vivid due to the excellent reflection of light from the facets. The precise facet arrangement allows for an even distribution of light, making the diamond sparkle brilliantly from every angle.
How to View the Hearts & Arrows Pattern
To properly observe the Hearts & Arrows pattern, the diamond needs to be viewed under specific conditions and using the right tools. A Hearts & Arrows viewer (a device designed to allow you to view the diamond from specific angles) is typically used to magnify the diamond’s intricate details.

Viewing through the Crown
Looking down at the diamond from above, through the crown, you should see eight arrow-shaped patterns radiating from the centre. This is the primary visual cue for the Hearts & Arrows pattern.
Viewing through the Pavilion
When looking up at the diamond from the pavilion, you should see eight heart shapes, arranged symmetrically. This view showcases the other half of the pattern and is often considered the most striking visual impression of the diamond’s symmetry.
Why Choose a Hearts & Arrows Diamond?
Diamonds with the Hearts & Arrows pattern are highly prized for their exquisite symmetry, which translates into superior light performance and overall beauty. While the pattern itself doesn’t necessarily guarantee an Ideal Cut grade, it does signal that the diamond has undergone careful craftsmanship and is likely to be visually appealing and highly reflective.

Advantages of Hearts & Arrows Diamonds:
Superior Sparkle – The perfect alignment of facets ensures that the diamond exhibits maximum brilliance and fire, making it incredibly eye-catching.
Exceptional Symmetry – The precise symmetry creates a balanced and harmonious appearance, resulting in a diamond that looks perfectly proportioned.
Symbol of Quality – The Hearts & Arrows pattern is often associated with diamonds of the highest craftsmanship, making them highly sought after by collectors and those looking for premium-quality diamonds.

July, 2017February, 2025

Hardness

Understanding the Durability of Diamonds
Hardness refers to a material’s resistance to scratching or abrasion. When it comes to diamonds, this property is particularly significant, as diamonds are known for being the hardest naturally occurring material on Earth. The hardness of a material is typically measured using Mohs Scale of Mineral Hardness, which rates materials based on their ability to scratch others.

Diamond’s Position on Mohs Scale
Diamonds score a perfect 10 on the Mohs scale, placing them at the top of the hardness scale.
This means that diamond can scratch all other materials, but it is unable to be scratched by any other known substance.
What Does Diamond Hardness Mean for Practical Use?
The hardness of diamond is one of the key reasons why it is the ideal choice for jewellery, especially in engagement rings and other precious items worn daily.

Key Benefits of Diamond Hardness:
Resistant to Scratching

The extreme hardness of diamonds ensures that they remain sharp and polished for many years without suffering from scratches, which would diminish their beauty and clarity.
This is especially important for diamonds set in jewellery, as they are exposed to wear and tear from daily activities.
Preservation of the Diamond’s Aesthetic Appeal

The ability of diamonds to maintain their brilliance and fire over time is largely attributed to their hardness. Since diamonds resist scratches, they maintain their faceted surfaces and polish, ensuring that the stone continues to reflect light optimally.
Long-Lasting Investment

Hardness contributes to the long-term durability of diamonds, which can be passed down through generations without significant wear. This makes diamonds an ideal choice for heirlooms and family treasures.
Resistant to Common Household Items

Everyday items such as keys, coins, and even some metals can scratch softer gemstones, but they won’t affect the surface of a diamond. This resilience makes diamonds perfect for engagement rings and wedding bands that are worn constantly.
Hardness vs. Toughness: Understanding the Full Picture
While hardness refers to a material’s resistance to scratching, toughness refers to its ability to resist breaking, chipping, or cracking. While diamonds are the hardest material on Earth, they are not the toughest.

Key Differences:
Hardness (measured on Mohs scale) only measures resistance to scratches, not the ability to withstand sudden impacts or stress.
Toughness, on the other hand, is a measure of a material’s ability to absorb energy and deform without fracturing.
Although diamonds are incredibly hard, they are brittle due to their crystalline structure. This means that diamonds can fracture if subjected to sharp impacts or if they experience extreme pressure in the wrong direction, especially along the cleavage planes where the crystal structure is weakest.

Example:
A diamond may resist scratches from a metal object, but it could shatter or chip if struck with a hammer or dropped on a hard surface.

Diamond Toughness and Its Impact on Cutting
When diamonds are being cut or shaped, a gem cutter must consider the diamond’s cleavage planes—the lines where the crystal structure is most likely to break under stress. A diamond is not just cut for its shape but also to preserve its toughness, as these cleaving directions need to be avoided during the cutting process to ensure that the diamond does not chip or break.

Facet Placement: When cutting a diamond, a skilled gem cutter will place the facets in such a way that they avoid the cleavage planes, thereby maintaining both hardness and toughness.

Precision and Care: The process requires great precision, as even the smallest error can result in a flawed or damaged stone.

How Does Diamond Hardness Compare to Other Materials?
Diamonds are not only the hardest gemstone, but also the hardest naturally occurring substance when compared to other materials. Here’s a look at how diamonds compare to other materials on the Mohs scale:

Material Hardness (Mohs Scale)
Diamond 10
Corundum (Ruby, Sapphire) 9
Topaz 8
Quartz 7
Orthoclase Feldspar 6
Apatite 5
Fluorite 4
Apatite 3
Calcite 3
Talc 1
Diamond’s Hardness Advantage

The next hardest material, corundum (rubies and sapphires), ranks at 9 on the scale, meaning diamonds are significantly harder.
Even common materials like glass or steel are much softer than diamonds, which is why diamond is commonly used in cutting tools for other materials.
What Does Diamond Hardness Mean for Jewellery Care?
While diamonds are extremely resistant to scratches, they still require proper care to prevent damage due to impacts or stress. Here are a few tips for ensuring the long-lasting beauty and durability of your diamond jewellery:

Avoid Hard Impacts: While diamonds are the hardest material, they can still chip or break if struck sharply. Be cautious when handling diamonds, especially when they are set in jewellery.
Store Separately: To avoid scratching, store diamonds separately from other jewellery or harder materials. Consider using a soft pouch or compartment in a jewellery box.
Regular Cleaning: Regularly clean your diamond jewellery to remove dirt or oils that could dull its appearance. Avoid abrasive cleaning methods that could scratch the diamond or the setting.

July, 2017February, 2025

Head

The Distinctive Feature of a Pear Cut Diamond
The head of a pear cut diamond refers to the wider, rounded end of the stone, which forms part of its unique, teardrop-like shape. The pear cut, also known as the tear drop cut, combines the round shape of a brilliant cut with the elongated point of a marquise cut, creating a delicate and graceful silhouette.

Characteristics of the Pear Cut Diamond’s Head
The head of a pear cut diamond is one of the most defining features of the shape. It is the broad, rounded portion of the diamond, which gives the stone its signature teardrop or drop-like appearance. The head contrasts with the narrower, pointed end, adding to the overall symmetry and elegance of the shape.

Key Features of the Head:
Wider and Rounded – The head is the portion of the pear cut diamond that appears wider and more rounded compared to the tapered point at the opposite end.
Central Focus – Often, the head serves as the focal point of the diamond’s visual appeal, drawing attention with its fuller, curvier look.
Smooth Contour – The rounded head typically has a smooth, soft curve, contributing to the overall fluid and graceful silhouette of the pear shape.
The Role of the Head in the Pear Cut Diamond’s Symmetry
For a pear cut diamond to achieve its desired elegance and balance, the head plays a crucial role in creating the overall symmetry of the stone. A well-proportioned head ensures that the pear cut appears harmonious and elegant.

Proportions and Symmetry
A well-shaped pear cut diamond will have a rounded head that gently tapers to a point, with the broadest part of the diamond located near the centre of the head.
The length-to-width ratio of a pear cut diamond should be in harmony, so the head does not appear disproportionately wide or narrow compared to the rest of the stone.
Symmetry is key in pear-shaped diamonds, and a properly shaped head can help avoid the stone looking lopsided or asymmetrical.
The Head in Relation to the Overall Design and Setting
The head of a pear cut diamond is not just a focal point of the stone but also an important consideration when setting the diamond in jewellery. Whether the diamond is used in an engagement ring, pendant, or earrings, the head’s design and placement within the setting can influence how the diamond is perceived.

Pear Cut Diamond in Engagement Rings
Positioning of the Head: The head is typically placed on top of the setting, where it will be most visible. The rounded end of the pear cut can be positioned either up or down, depending on the wearer’s personal preference or the overall design.
Setting Choices: The head’s curves and broad shape can complement certain settings, such as a halo or solitaire setting, accentuating the diamond’s natural shape.
Visual Impact: A well-positioned head can make the diamond appear larger and more elongated than a round cut, giving the overall piece a more elegant, sophisticated look.
How the Head Affects the Diamond’s Appearance
The head of the pear cut diamond contributes significantly to the visual appeal of the entire stone. Its rounded, fuller shape helps to create a sense of softness and elegance while maintaining a level of boldness due to its unique teardrop form.

Light Reflection and Sparkle
The head plays an important role in the way the diamond reflects light. A well-shaped head allows the diamond to catch light from different angles, increasing its brilliance and fire.
The broader end of the pear cut may also help create a sense of depth in the diamond, making it appear more dynamic and multifaceted.
The Head’s Impact on Size Perception
Because the pear cut is elongated, it can give the impression of a larger diamond, even with a lower carat weight. The head contributes to this perception of size, especially when paired with long, thin sides.
Considerations When Evaluating the Head of a Pear Cut Diamond
When evaluating the head of a pear cut diamond, several factors should be considered to ensure the diamond is of high quality and its proportions are well-balanced.

1. Symmetry and Shape
A well-shaped head should appear smooth and rounded, without any noticeable flat spots or sharp angles.
Lopsided heads or irregular shapes can make the diamond appear uneven or less symmetrical.
2. Size and Proportions
The size of the head should be proportionate to the overall length of the pear cut. If the head is too wide or too narrow, it can disrupt the diamond’s overall symmetry and appearance.
Ideally, the length-to-width ratio should fall between 1.45 and 1.75 to maintain balance and avoid a bulky or overly elongated look.
3. Polish and Finish
The polish of the head is also important to ensure that the surface is smooth and free from any noticeable blemishes or scratches that could affect the diamond’s brilliance.

July, 2017February, 2025

Graining

The Natural Growth Patterns in Diamonds
Graining refers to faint wavy, hazy, oily, or shadow-like lines that can appear inside a diamond or on its surface. These patterns result from irregular growth and crystallisation during the diamond’s natural formation deep within the Earth. Graining is sometimes referred to as “growth lines” or “growth marks”, and it can affect a diamond’s clarity, transparency, and overall visual appearance.

What Causes Graining in Diamonds?
Diamonds form over millions to billions of years under extreme heat and pressure deep in the Earth’s mantle. However, not all diamonds grow perfectly. Occasionally, crystallographic irregularities occur, leading to graining. These irregularities may be caused by:

Uneven atomic growth – Fluctuations in temperature and pressure can cause the diamond’s crystal structure to develop inconsistencies.
Interrupted crystallisation – When a diamond pauses in its growth and then resumes, it may form internal distortions.
Mineral inclusions or impurities – Elements such as nitrogen or boron present during formation can contribute to the development of visible graining.

Types of Graining in Diamonds
Graining can appear in various forms, affecting both internal clarity and surface quality. The four main types of graining are:

1. Internal Graining
Appears as faint lines, streaks, or wispy distortions within the diamond.
Can be colourless, white, brown, or reflective.
Sometimes mistaken for inclusions but differs as it follows the diamond’s crystal structure rather than being a foreign substance.
2. Surface Graining
Found on the external facets of the diamond.
Can resemble polishing marks, light scratches, or subtle indentations.
May not be visible to the naked eye but can be detected under 10x magnification.
3. Reflective Graining
A more pronounced form of internal graining where light reflects off the growth lines, making them more noticeable.
Can create a slightly hazy or cloudy appearance in certain lighting conditions.
4. Coloured or Dark Graining
Caused by trace elements within the diamond or due to strain in the crystal structure.
Can appear as brown, grey, or dark shadow-like lines.
More commonly found in diamonds with strong fluorescence or high nitrogen content.
How Does Graining Affect a Diamond’s Appearance and Value?
Impact on Clarity

Internal graining can be noted on a grading report, particularly in diamonds with VS (Very Slightly Included) clarity or lower.
If graining is very faint, it may not impact the clarity grade but could still be mentioned in the report.
Impact on Transparency & Brilliance

Strong graining can cause the diamond to appear milky, hazy, or oily, reducing its transparency.
It may affect the way light travels through the diamond, diminishing brilliance and fire.
Impact on Diamond Grading Reports

Independent gemological laboratories such as DCLA, GIA, and IGI may list graining as a comment in the clarity characteristics section of a diamond grading report.
If graining is significant, it may contribute to a lower clarity grade.
Impact on Value

Diamonds with minor or faint graining typically do not experience a significant drop in value.
However, diamonds with heavy graining or visible haziness may be less desirable and priced lower than those with better transparency.
How to Identify Graining in a Diamond
Graining is often invisible to the naked eye but can be detected through:

10x Magnification – Jewelers and gemologists use a loupe or microscope to identify fine growth lines.
Diamond Grading Reports – If present, graining will be noted in the report’s clarity characteristics section.
Lighting Tests – Shining a bright light through the diamond may reveal hazy areas or faint wavy lines.

Can Graining Be Removed or Minimized?
Recutting & Repolishing – Surface graining may be improved by polishing or re-cutting the diamond, but this reduces carat weight.
Proper Cleaning & Maintenance – A clean diamond can help reduce the visual impact of light surface graining.
Choosing a Well-Cut Diamond – A diamond with excellent cut proportions can help mask minor graining by maximizing brilliance.

Is Graining a Dealbreaker When Buying a Diamond?
Not necessarily. Mild or faint graining has little to no impact on a diamond’s overall beauty, especially if it is only visible under magnification. However, strong graining that affects transparency and brilliance may be a concern.

Always check the grading report and view the diamond in person before purchasing. If you are unsure, consult with a certified gemologist or independent diamond expert for a professional opinion.

July, 2017February, 2025

Green Diamond

A Rare and Unique Natural Treasure
A green diamond is a diamond that exhibits a natural green body colour, making it one of the rarest and most sought-after coloured diamonds in the world. For a diamond to be classified as a true green diamond, green must be the dominant hue, although it may have secondary modifying tones of yellow, blue, or grey.

These remarkable diamonds owe their distinctive green hue to exposure to natural radiation deep within the Earth’s crust over millions of years. The radiation interacts with the diamond’s atomic structure, creating unique structural defects that result in its green coloration. Because of the highly specific and rare conditions required for their formation, natural green diamonds are exceptionally rare and valuable.

Formation of Natural Green Diamonds
Unlike most coloured diamonds, which owe their colour to trace elements (such as boron in blue diamonds or nitrogen in yellow diamonds), green diamonds derive their colour from natural irradiation.

How it Happens:

Natural Radiation Exposure: Over millions of years, the diamond is exposed to radioactive minerals such as uranium or thorium in the Earth’s crust.
Structural Alterations: The radiation disrupts the arrangement of carbon atoms in the diamond’s crystal lattice, creating a “radiation-induced colour centre.”
Absorption of Light: These defects allow the diamond to absorb red and yellow light, making the diamond appear green to the human eye.
Key Fact: The green colour usually forms on the surface of the rough diamond, which means that careful cutting is required to preserve the colour in the final polished gem.

Shades & Intensity of Green Diamonds
Like all fancy-coloured diamonds, green diamonds are graded based on hue, tone, and saturation. The most valuable green diamonds have a pure green hue with strong saturation. However, many natural green diamonds exhibit secondary modifying tones that affect their final colour.

Green Diamond Colour Classifications:
Colour Name Description Common Secondary Hues
Fancy Light Green Soft, pastel green colour Yellow, Grey
Fancy Green True green with medium saturation Yellow, Blue
Fancy Intense Green Vibrant, rich green hue Blue, Yellow
Fancy Vivid Green Deep, highly saturated green Minimal or No Modifying Tones
Fancy Deep Green Darker green with strong depth Grey, Yellow
The rarest and most valuable green diamonds are those with a strong, pure green hue and minimal secondary modifiers.

Famous Green Diamonds
Due to their rarity, natural green diamonds have become legendary in the world of gemstones. Some of the most famous examples include:

The Dresden Green Diamond (41.00 ct)

One of the most famous and largest natural green diamonds in existence.
Weighing 41.00 carats, it exhibits a pure green colour with exceptional clarity.
Believed to have originated in India, it is now housed in Germany’s Green Vault museum.
The Aurora Green Diamond (5.03 ct)

The largest Fancy Vivid Green diamond ever auctioned.
Sold for $16.8 million at Christie’s in 2016.
The Ocean Dream Diamond (5.51 ct)

A unique blue-green diamond with a distinctive Fancy Deep Blue-Green colour.
Exhibits a combination of radiation exposure and boron content.
The Chopard Green Diamond (10.02 ct)

A Fancy Intense Green diamond set in a ring by Chopard.
One of the most valuable green diamonds in the world.
How Are Green Diamonds Graded?
Green diamonds are graded based on the 4Cs (Carat, Colour, Clarity, and Cut), with special emphasis on colour intensity.

Hue: The primary colour must be green, though modifying hues like yellow, blue, or grey may be present.
Tone: Determines how light or dark the green appears.
Saturation: The strength or intensity of the green hue—more saturated stones are more valuable.

Laboratories like the GIA (Gemological Institute of America) and DCLA (Diamond Certification Laboratory of Australia) provide certificates to verify a green diamond’s natural origin.

Treated vs. Natural Green Diamonds
Because natural green diamonds are incredibly rare, some diamonds undergo treatments to enhance or artificially create a green hue. These treatments include:

Radiation Treatment – Exposing diamonds to artificial radiation to mimic natural colouration.
HPHT (High Pressure, High Temperature) Processing – Alters the internal structure to change colour.
Coating – Applying a thin layer of green material to the diamond’s surface.
Key Buyer’s Tip: Always verify that a green diamond’s colour is natural by requesting a grading report from an independent, recognised gemological laboratory (such as DCLA or GIA).

Are Green Diamonds a Good Investment?
Extreme Rarity – Natural green diamonds are among the rarest coloured diamonds, making them highly desirable.
High Market Demand – Prices for Fancy Vivid Green diamonds have consistently increased over time.
Auction Record Breakers – Green diamonds regularly fetch millions at auctions.

The most valuable green diamonds are Fancy Intense or Fancy Vivid Green with minimal secondary hues and strong saturation.

July, 2017February, 2025

Grading Report

Grading Report: The Blueprint of a Diamond’s Quality
A grading report, also known as a diamond certificate, is an official document issued by a recognised and independent diamond grading laboratory. It provides a detailed, unbiased assessment of a diamond’s characteristics based on internationally accepted grading standards.

This report plays a critical role in determining a diamond’s quality, authenticity, and market value, allowing buyers, sellers, and investors to make informed decisions.

What is Included in a Diamond Grading Report?
A diamond grading report contains a comprehensive analysis of a diamond’s physical and optical properties. The following elements are typically included:

1. Identification Details
Report Number – A unique serial number assigned to the diamond, used for tracking and verification.
Date of Examination – The date the diamond was graded.
Laboratory Name & Logo – Ensures authenticity and trustworthiness of the certification body (e.g., DCLA, GIA, IGI, HRD).
2. The 4Cs of Diamond Grading
Carat Weight – The diamond’s exact weight, measured to the nearest hundredth of a carat.
Cut Grade – Evaluates the diamond’s proportions, symmetry, and polish, impacting its brilliance and fire.
Colour Grade – Determines how colourless the diamond is, graded on a scale from D (colourless) to Z (light yellow/brown).
Clarity Grade – Assesses internal inclusions and surface blemishes, ranging from Flawless (FL) to Included (I3).
3. Additional Diamond Characteristics
Shape & Cutting Style – Specifies the diamond’s shape (e.g., round, princess, oval) and cut style.
Measurements – Precise dimensions of the diamond, including diameter, table size, and depth.
Girdle Thickness – Evaluates the diamond’s girdle proportion (thin, medium, thick).
Culet Size – Determines if the bottom facet (culet) is pointed, small, or large.
Polish & Symmetry – Rates how well the diamond’s facets are cut and aligned, affecting its sparkle.
Fluorescence – Indicates if the diamond emits a glow under UV light, rated from None to Strong.
4. Diamond Proportions & Light Performance
Proportion Diagram – A detailed illustration showing the diamond’s exact cut proportions.
Light Performance Analysis (in some reports) – Shows how effectively the diamond reflects light.
5. Clarity Characteristics Plot (Inclusion Map)
A diagram indicating the type, location, and size of inclusions or blemishes.
Helps identify the diamond and distinguish it from others.
6. Comments & Additional Features
Any unique observations about the diamond, such as laser inscriptions or special cutting techniques.
7. Security Features & Verification
Some reports contain laser-engraved serial numbers on the girdle for easy identification.
Advanced security features like holograms, QR codes, and online verification portals ensure authenticity.
Grading Report vs. Appraisal: What’s the Difference?
Many people mistakenly believe a grading report and an appraisal are the same, but they serve different purposes:

Feature Grading Report Appraisal
Issued By Independent gemological laboratory (e.g., GIA, DCLA, IGI) Jewellery appraiser or valuation expert
Purpose Determines the diamond’s quality Assigns a monetary value for insurance, resale, or probate
Contains a Value? No monetary value Includes an estimated market value
Objectivity Completely unbiased May be influenced by market trends or jeweller pricing
Validity Period Permanent Needs updating over time due to price fluctuations
A diamond grading report is not an appraisal—it does not assign a price to the diamond but provides an objective assessment of its quality and characteristics.

Why is a Grading Report Important?
Ensures Trust & Transparency
Provides a scientific, unbiased evaluation of the diamond’s quality.
Helps prevent fraud or misrepresentation by verifying the diamond’s true attributes.
Helps Determine Market Value
A certified diamond holds more value than an uncertified one.
Allows buyers to compare diamonds based on verified grading standards.
Essential for Insurance & Resale
Insurance companies require a grading report to determine coverage and replacement value.
A report helps sellers accurately price and market their diamond.
Prevents Overpaying
Ensures buyers are not paying for a diamond that does not match its advertised quality.
Helps investors and collectors make informed purchases.
Which Laboratories Issue Grading Reports?
Only independent and reputable gemological laboratories should issue a grading report. Some of the most respected names in the industry include:

DCLA (Diamond Certification Laboratory of Australia) – The official CIBJO laboratory for Australia, known for strict and consistent grading.
GIA (Gemological Institute of America) – One of the most widely recognised authorities in diamond grading.
IGI (International Gemological Institute) – Popular for grading both natural and lab-grown diamonds.
HRD (Hoge Raad voor Diamant, Belgium) – Known for high standards in diamond certification.

Always check the laboratory’s reputation before relying on a grading report, as some lesser-known labs may have looser grading standards.

July, 2017February, 2025

Grainer

A Traditional Unit of Diamond Weight Measurement
The term “grainer” is used in the diamond industry to describe a diamond’s weight in quarter-carat (0.25 ct) increments. It is derived from an ancient method of weighing gemstones and precious materials using natural seeds or grains.

In historical gemstone trading, the weight of diamonds was originally measured in grains of wheat or rice before the adoption of the metric carat system. One carat (1.00 ct) was equivalent to four grains of rice, leading to the term “four grainer” for a 1.00-carat diamond (4 × 0.25 ct = 1.00 ct).

Understanding the Grainer System in Diamond Weight
The grainer system remains a widely used traditional unit in the diamond industry, particularly among traders, jewellers, and manufacturers.

Grainer Diamond Weight (Carats) Description
One Grainer 0.25 ct A small diamond often used in accent stones or cluster settings.
Two Grainer 0.50 ct A half-carat diamond, popular for jewellery.
Three Grainer 0.75 ct A diamond nearing the one-carat mark.
Four Grainer 1.00 ct A full-carat diamond, a benchmark size in the industry.
Eight Grainer 2.00 ct A two-carat diamond, considered a luxury size.
Since carat weight affects the value of a diamond exponentially, rather than linearly, a four grainer (1.00 ct) diamond is worth significantly more than four one-grainer (0.25 ct) diamonds of the same quality.

Historical Origins of the Grainer System
1. Early Trade and Natural Measurement
Before precise gemstone scales, ancient traders used grains of wheat, rice, or carob seeds to determine gemstone weight.
The carob seed was particularly favoured due to its uniform size and weight, eventually leading to the development of the carat system.
2. The Transition to Carats
Over time, the industry standardised the weight of one carat to 200 milligrams (0.200 grams).
The term “grainer” persisted, especially in wholesale diamond trading and manufacturing, as it provided a quick reference for size estimation.
Modern Usage of the Grainer System
1. Wholesale Diamond Trading & Pricing
Grainer terminology is common among diamond dealers, particularly in India, Antwerp, New York, and Hong Kong.
Traders often negotiate diamond prices in terms of grainers rather than carat weight.
2. Diamond Sorting & Manufacturing
In diamond cutting and sorting, rough diamonds are categorised into grainers to estimate how they will be cut into polished stones.
Rough diamonds may be described as one-grainer rough (0.25 ct) or four-grainer rough (1.00 ct), depending on their potential yield.
3. Jewellery Design & Setting
Accent stones in rings, earrings, and bracelets are often measured in grainers rather than carats for precision.
For example, a tennis bracelet may contain 20 two-grainers (0.50 ct each), totalling 10.00 carats.
Why the Grainer System Still Matters Today
Quick Size Reference – Allows jewellers and traders to communicate diamond weights efficiently.
Tradition & Heritage – Preserves historical methods of diamond measurement.
Practical for Diamond Sorting – Helps manufacturers categorise and plan rough diamond cutting.

Although modern diamond transactions primarily use the metric carat, the grainer system remains a valuable industry standard, particularly in wholesale and manufacturing sectors.