Glossary – Page 2 – The Diamond Certification Laboratory of Australia (DCLA)

July, 2017February, 2025

Tone

Tone refers to the degree or depth of colour in a diamond, specifically indicating its lightness or darkness. It is one of the three main factors used to grade the colour of diamonds, alongside hue (the actual colour) and saturation (the intensity of the colour). Tone plays a significant role in determining how the colour of a diamond appears and contributes to its overall beauty.

In the context of coloured diamonds, tone describes the extent to which the diamond’s colour approaches white on the light end of the scale, or black on the dark end. This gradation allows for a more nuanced understanding of the diamond’s colour, as it can help distinguish between diamonds that have a pale, subtle hue and those that have a much richer, deeper colour.

Understanding Tone in Coloured Diamonds:
Lightness vs. Darkness:

Light Tone: Diamonds with a light tone will appear closer to white or have a very pale version of their characteristic colour. For example, a light blue diamond might appear almost colourless, with just a hint of blue.
Dark Tone: A dark tone refers to a deeper, more intense colour, where the diamond will have a noticeable and striking shade, such as a deep blue or rich red. These diamonds have less of a white appearance and are generally more visually saturated with their primary colour.
Tone Scale:

Diamonds are typically graded on a tone scale that ranges from very light to very dark. The scale helps to categorise the degree of tone, making it easier to assess the overall colour quality of the diamond.
For example, a diamond with a very light tone might appear almost colourless or faintly tinted, while a dark tone would exhibit a much more vivid, intense hue.
Effect of Tone on Overall Appearance:

The tone of a coloured diamond influences how the colour is perceived by the naked eye. A diamond with a light tone may appear subtler or more delicate, while a dark tone may seem more bold and vibrant.
Diamonds that have a medium tone tend to be the most desirable for many coloured diamonds, as they strike a balance between richness of colour and visual appeal. Too light a tone may result in a lack of colour intensity, and too dark a tone can sometimes make the diamond appear more opaque, reducing the brilliance and sparkle.
Tone in Coloured Diamond Grading:

The grading of a coloured diamond takes into account all three key aspects—hue, saturation, and tone—to assess the overall quality of the colour. When the tone is more intense or dark, it can add to the value of the diamond, especially if the other factors (hue and saturation) are also high.
For example, a fancy blue diamond with a medium-to-dark tone might be more valuable than a fancy blue diamond with a very light tone, as the deeper tone is generally more desirable in the market.
Relation to Colourless Diamonds:

Tone is not a concept that is typically applied to colourless diamonds, as their grading is based more on their lack of colour (i.e., the GIA diamond colour scale for colourless diamonds goes from D to Z, with D being completely colourless and Z showing noticeable yellow or brown hues). However, tone is crucial in the grading of coloured diamonds like pink, blue, green, yellow, and other fancy coloured diamonds.
Examples of Tone in Coloured Diamonds:
Light Pink Diamond: A light pink diamond has a tone that may be closer to white with just a hint of pink. This creates a subtle and delicate appearance, often preferred in engagement rings for a more understated, soft aesthetic.

Dark Red Diamond: A dark red diamond, on the other hand, may have a tone that is deep and intense, appearing closer to burgundy or wine. This deeper tone makes the red colour more prominent, resulting in a striking, dramatic effect in jewellery.

Medium Blue Diamond: A medium blue diamond has a balanced tone that allows the blue hue to be seen clearly while still allowing for the brilliance and sparkle to shine through. These diamonds are often considered highly desirable as they possess the ideal balance of tone and saturation.

Impact of Tone on Diamond Value:
Light Tone: Coloured diamonds with a light tone (closer to white) may be less valuable than those with deeper, more saturated tones, as they have less of the characteristic colour that makes the diamond unique. For example, a light yellow diamond may be less expensive than a canary yellow diamond.

Dark Tone: While a dark tone can sometimes enhance the colour of a diamond, it can also diminish its brilliance if the tone is too dark. A diamond that is too dark in tone may look more opaque and lose some of the sparkle that is typically associated with diamonds.

Medium Tone: Diamonds with a medium tone often offer a desirable balance, providing enough colour intensity while still allowing the light to pass through and reflect off the facets. These diamonds tend to be the most sought-after, with a strong visual presence without overwhelming the viewer.

Tone plays a crucial role in determining the appearance and value of a coloured diamond. It refers to the lightness or darkness of the diamond’s colour and can range from very pale to very dark. When evaluating a coloured diamond, tone, alongside hue and saturation, is considered to determine its overall colour quality. The ideal tone depends on the type of coloured diamond, with many people preferring diamonds with a medium tone for their balance of colour richness and brilliance.

July, 2017February, 2025

Toughness

$Toughness Measure of brittleness, or resistance to fracture and breaking$

Toughness refers to a diamond’s resistance to fracture or breaking when subjected to impact or stress. While diamonds are known for their exceptional hardness, which allows them to resist scratching and abrasion, toughness measures how well a diamond can withstand physical force, such as chipping or cracking. Toughness is an essential characteristic when evaluating the durability of a diamond, particularly when it comes to everyday wear and usage in jewellery.

Though diamonds are one of the hardest materials on Earth, they are not immune to damage. Due to the crystal structure of diamonds, they have certain planes of weakness that can make them susceptible to breaking if impacted along these planes. Therefore, while a diamond may not scratch easily, it can still fracture or split under the right conditions. This makes toughness an important factor in assessing how a diamond will perform in real-world scenarios, such as in rings or other jewellery that is regularly exposed to physical stress.

Understanding Diamond Toughness:
Hardness vs. Toughness:

Hardness refers to a material’s ability to resist scratching, and diamonds are the hardest known natural substance, scoring a 10 on the Mohs scale of hardness.
Toughness, on the other hand, refers to how well a material can absorb energy without breaking or fracturing. While diamonds are incredibly hard, they are not as tough as some other materials due to their brittleness. This means that while diamonds can resist scratching, they may be more prone to chipping or cracking if hit at certain angles.
Directional Hardness:

One of the key factors influencing the toughness of a diamond is its directional hardness. Diamonds have a crystal structure known as cubic or isometric, which means that their atoms are arranged in a specific way that makes them incredibly hard in certain directions but more vulnerable in others.
While the diamond is extremely hard along its axes, this structural alignment can make it more prone to cleaving or splitting along certain planes, especially when it experiences a strong impact. These planes of weakness make diamonds more fragile in some situations, particularly if subjected to sharp blows or pressure.
Toughness Rating:

Diamonds do not have a standard toughness rating in the same way that they are graded for hardness. However, toughness is typically described in terms of how resistant a diamond is to breaking, chipping, or fracturing.
Toughness can be affected by factors such as the quality of the cut, inclusions, and fractures present in the diamond. A diamond with significant internal flaws, such as inclusions, may be less tough and more likely to break or chip under stress than a flawless diamond.
Factors Influencing Diamond Toughness:

Clarity: Diamonds with inclusions or internal fractures are generally more prone to breakage. These internal weaknesses can compromise the diamond’s toughness, making it more vulnerable to impact.
Cut Quality: A well-cut diamond with proper proportions and symmetry will often be more durable, as the cut will reduce the likelihood of creating stress points where fractures could occur. A poorly cut diamond may have internal tensions that make it more fragile.
Size and Shape: Larger diamonds or diamonds with more complex shapes (like those with sharp corners or thin edges) may be more susceptible to chipping or fracturing if impacted. The shape and overall structure of the diamond can affect its ability to absorb force without damage.
Real-World Application:

While diamonds are the hardest known material, their brittleness means that they need to be handled with care. Diamonds used in jewellery, such as engagement rings or bracelets, are typically designed to avoid exposure to significant impact or stress.
For example, diamonds with sharp corners (like princess cut diamonds) or thin edges (like emerald cut diamonds) may be more susceptible to chipping than those with rounder shapes, such as the round brilliant cut, which typically has a stronger overall structure.
Bezel settings or halo settings in jewellery can offer additional protection to the diamond, keeping it shielded from accidental impact.
Toughness in Coloured Diamonds:

While most of the principles regarding diamond toughness apply to colourless diamonds, coloured diamonds may have their own unique challenges. For example, some coloured diamonds, especially those with intense colours like red or blue, may have inclusions or internal characteristics that affect their toughness.
Coloured diamonds, due to their often unique internal structures, may exhibit slightly different behaviour under impact, but they still share the same basic brittleness as other diamonds.
Toughness and Diamond Jewellery:

When choosing a diamond for daily wear jewellery, toughness is an important consideration, especially for items like engagement rings, which are subject to constant wear and potential impact.
A diamond’s setting also plays a role in how well it can withstand rough treatment. A prong setting, for example, may expose the diamond to more risk of damage, while a bezel setting can offer more protection.

Diamond toughness is an essential characteristic that determines a diamond’s ability to withstand impact and stress without fracturing or breaking. Although diamonds are the hardest material on Earth, their brittleness means they can still break along planes of weakness in their crystal structure. Therefore, toughness is closely linked to hardness but involves how well a diamond resists fractures, chips, and cracks from physical force. When choosing a diamond for jewellery, it is important to consider the diamond’s clarity, cut, and shape, as these factors can influence the diamond’s overall toughness and resistance to damage.

July, 2017February, 2025

Table

The table is one of the most important facets of a polished diamond, situated at the very top of the diamond, in the crown area. It is the largest flat facet on the diamond and plays a crucial role in how light interacts with the stone. The table facet is typically positioned parallel to the girdle, which is the outermost edge of the diamond, and it serves as a window through which light enters and exits the diamond. The size and proportion of the table facet significantly impact the overall appearance, brilliance, and sparkle of the diamond.

Position and Shape:
The table is flat and circular in shape, with its size and dimensions typically defined as a percentage of the diameter of the diamond, measured from the girdle.
It is placed directly at the top of the diamond, centered on the crown. For round brilliant cut diamonds, the table should be symmetrical to allow for even light reflection and maximum brilliance.
The size of the table relative to the overall dimensions of the diamond is an important factor in its overall cut quality and light performance. A table that is too large or too small can negatively affect the diamond’s visual appeal.
Role of the Table in Diamond Brilliance:
The table facet is the primary surface through which light enters the diamond, and its quality directly influences the diamond’s brilliance (the amount of white light reflected). Light entering the table facet is refracted through the diamond’s other facets, creating the sparkle and life that is characteristic of a well-cut diamond.
If the table is too large, it may result in excessive light leakage, where light passes through the bottom of the diamond, reducing its brilliance. Conversely, a table that is too small may limit the diamond’s ability to reflect light effectively, making the diamond appear darker or less vibrant.
Table and Diamond Cut Quality:
The size of the table is one of the key factors considered when assessing a diamond’s cut grade. The table-to-depth ratio is calculated by measuring the table’s diameter and comparing it to the diamond’s overall depth. An ideal round brilliant cut diamond typically has a table size that falls within a certain percentage range of its overall diameter, usually between 53% and 58% for optimal brilliance.

Ideal Table Size: For round brilliant cut diamonds, an ideal table size typically falls between 53% and 58% of the overall diameter, balancing light reflection and maximizing brilliance.
Large Table: A diamond with an excessively large table relative to its depth may reflect less light, leading to a loss of brilliance and a flat appearance. In contrast, a smaller table could result in a diamond that looks darker or less reflective.
Table in Fancy Shapes:
While the table is a key feature in all diamonds, it is especially important for round brilliant cut diamonds. In fancy-shaped diamonds, such as princess, emerald, and asscher cuts, the table may vary slightly in shape and size to accommodate the unique proportions and angles of each cut. However, the role of the table in influencing light entry and brilliance remains consistent across all diamond shapes.

DCLA and Table Quality:
The Diamond Certification Laboratory of Australia (DCLA) is one of the leading authorities in diamond grading and certification, particularly within the Australian market. When a diamond is graded by DCLA, the table is assessed as part of the overall cut grade. DCLA uses a comprehensive set of criteria to evaluate all facets of the diamond, including the table facet.

The table is evaluated for size, symmetry, and alignment, ensuring that it contributes to the overall quality of the cut and the diamond’s ability to reflect light properly.
DCLA reports provide detailed information about the table size in relation to the diamond’s total diameter, helping consumers and investors understand how the table contributes to the diamond’s brilliance and overall visual appeal.
DCLA also measures the proportions of the table and other facets, ensuring that the diamond meets industry standards for ideal proportions. The laboratory’s expertise in evaluating the table facet, alongside other critical attributes like crown angle and pavilion depth, ensures that each diamond receives a thorough and accurate grading report that reflects its true quality.

Table and Diamond Certification:
In the grading report issued by DCLA, the table facet is one of the important details that helps determine the diamond’s overall cut grade. Since the cut is a significant factor in determining the diamond’s beauty and value, the size, proportions, and finish of the table are carefully examined. A well-proportioned table enhances the diamond’s light performance, while an incorrect or poorly finished table can result in suboptimal visual appeal.

In addition to the table’s size, the report may also include additional information about the table’s polish, symmetry, and overall surface quality, as these factors all influence the diamond’s final appearance.

The table is a crucial facet in determining a diamond’s overall beauty and brilliance. Its size, shape, and position play a vital role in how the diamond interacts with light and contributes to the diamond’s overall sparkle and visual appeal. Whether it is a round brilliant cut diamond or a fancy shape, the quality and proportions of the table can significantly affect the diamond’s grade and value. The DCLA ensures that diamonds are thoroughly assessed and accurately graded, with special attention to the table’s impact on the diamond’s overall cut quality and performance.

July, 2017February, 2025

Table Size

Table size refers to the measurement of the table facet of a diamond, which is the large, flat surface located on the top of the stone. It is expressed as a percentage of the diameter of the diamond. The table size is a crucial factor in determining the overall appearance and brilliance of the diamond. It plays an essential role in balancing brilliance (the white light reflected from the diamond) and dispersion (the colourful flashes of light that come from the diamond’s facets).

Table Size and its Impact on Brilliance and Fire:
Brilliance: A well-proportioned table allows for an optimal amount of light to enter the diamond, reflect off the facets inside, and return to the viewer’s eye. The table size is an essential factor that helps to achieve maximum brilliance. When the table is too large, more light may leak out from the bottom of the diamond, reducing brilliance. A table that is too small may limit light reflection, resulting in a dull appearance.
Dispersion (Fire): Dispersion is the colourful flashes of light that a diamond emits when it is moved or viewed under direct light. The table size also affects how much dispersion is visible. A properly proportioned table will allow for the best balance between brilliance (white light) and fire (colourful flashes). If the table size is too large, it may decrease the intensity of the dispersion, as the light may not be effectively refracted and split into different colours.
How Table Size is Measured:
Table Size as a Percentage: Table size is typically expressed as a percentage, representing the diameter of the table facet in relation to the overall diameter of the diamond. For example, if the table diameter is 5mm and the overall diameter of the diamond is 8mm, the table size would be calculated as:
Table Size Percentage

Table Size Percentage=(85)×100=62.5%

This means the table facet makes up 62.5% of the total diameter of the diamond.
Ideal Table Size:
For round brilliant cut diamonds, the ideal table size typically falls within the 53% to 58% range of the diamond’s total diameter. This proportion allows for the best balance of light reflection and brilliance, ensuring the diamond appears vibrant and sparkling. When the table is within this ideal range, it enhances the diamond’s overall performance by optimising how it handles light.

Ideal Range: A table size between 53% and 58% is generally considered ideal for round brilliant cut diamonds. Diamonds with table sizes within this range tend to exhibit excellent brilliance and light performance.
Larger Table Sizes: A table size that is larger than 58% may reduce the amount of light that is reflected, resulting in lower brilliance. This can make the diamond appear flat and less lively.
Smaller Table Sizes: A table size smaller than 53% may limit the amount of light that enters the diamond, reducing its sparkle and making the diamond look darker or duller.
Table Size and Diamond Grading:
The table size is one of the factors assessed when determining the cut grade of a diamond, particularly in round brilliant cut diamonds. The cut grade reflects the overall quality of the diamond’s proportions, symmetry, and polish, and it has a significant impact on the diamond’s brilliance and value.

Proportions: Table size is a crucial part of the overall proportions of a diamond, and it works in conjunction with other factors such as crown angle, pavilion depth, and girdle thickness to determine the overall quality of the cut.
Diamond Certification: Leading diamond grading laboratories, such as the DCLA (Diamond Certification Laboratory of Australia), carefully assess the table size when providing a grading report. They ensure that the table size falls within an acceptable range for the diamond’s shape and type to guarantee the best possible visual performance.
Fancy-Shaped Diamonds and Table Size:
While table size is most commonly associated with round brilliant cut diamonds, it also applies to other fancy-shaped diamonds, such as emerald cut, asscher cut, princess cut, and oval cut diamonds. However, for fancy shapes, the ideal table size may vary depending on the shape and the proportions of the diamond. For example:

Princess Cut Diamonds: In a princess cut diamond, the table size is usually larger relative to the overall size, often in the 60% to 70% range. This helps to achieve the maximum brilliance and visual appeal.
Emerald Cut Diamonds: Due to their step-cut faceting, emerald cut diamonds tend to have a larger table relative to their overall size, often ranging from 60% to 70% as well. The larger table enhances the clarity of the diamond, allowing the observer to better appreciate its internal characteristics.
Factors Affecting Table Size:
Several factors can influence the size of the table facet on a diamond:

Cutting Style: The cutting style of the diamond affects the table size. Round brilliant cuts are often cut with a smaller table, while other cuts like princess and emerald may have larger tables.
Diamond Size: Larger diamonds often have larger table sizes, as their proportions allow for more substantial table facets without sacrificing the diamond’s brilliance.
Manufacturer Preferences: Some diamond manufacturers may adjust the table size to meet specific aesthetic or performance goals, influencing the final appearance of the diamond.

The table size of a diamond is a crucial factor that significantly influences its brilliance and fire. It is measured as a percentage of the diamond’s overall diameter, and its proper proportion ensures the diamond displays optimal light performance. For round brilliant cut diamonds, the ideal table size typically falls within the 53% to 58% range, although fancy-shaped diamonds may have varying table sizes depending on their unique cutting styles. Properly balanced table size, along with other critical cut factors, contributes to a diamond’s overall beauty, value, and appeal. The DCLA and other leading certification labs evaluate table size as part of the comprehensive cut grading process, ensuring that the diamond performs to its fullest potential.

July, 2017February, 2025

Step Cut

A step cut is a style of diamond cutting that creates a distinctive look with rows or steps of elongated facets. These facets run parallel to the girdle of the diamond on both the crown (the upper portion) and the pavilion (the lower portion). The step cut is known for its classic, elegant appearance and is often used in diamonds with larger surface areas.

Key Features of Step Cut Diamonds:
Faceting Style: The defining characteristic of the step cut is the linear arrangement of facets, which resemble steps or rows. These elongated facets create a staircase-like effect, with the facets running parallel to the girdle of the diamond. This cut contrasts with the brilliant cut, which features numerous triangular and kite-shaped facets to reflect light in a more dynamic way.

Popular Step Cuts: Two of the most famous step cut diamond shapes are the emerald cut and the baguette cut:

Emerald Cut: The emerald cut is a rectangular or square-shaped diamond with cut corners. It features large, rectangular facets that showcase the diamond’s clarity and colour. The emerald cut is known for its elegant, understated beauty.
Baguette Cut: Typically smaller and more elongated, the baguette cut features long, rectangular facets and is often used as an accent stone or in vintage-style jewellery.
Facets and Symmetry: In a step cut, the facets are typically rectangular and arranged in a way that each one is aligned with the others, creating a step-like appearance. These facets are often fewer in number than those found in brilliant cuts, which gives step-cut diamonds a more minimalist and elegant appearance.

Clarity Emphasis: Step cuts, particularly the emerald cut, are often chosen for diamonds with high clarity because they showcase internal inclusions more prominently than a round brilliant cut. The large, flat facets on step-cut diamonds allow for a clearer view into the diamond, making it important to choose a stone with minimal visible flaws for the best visual appeal.

Light Reflection: Unlike brilliant cuts, which are designed to reflect light in many directions to create sparkle, the step cut focuses on creating a more subdued, reflective appearance. The large facets reflect light in a more linear way, and while step-cut diamonds might not have the same intense sparkle as a round brilliant cut, they often display a unique glow that comes from the reflection of light off their smooth, flat surfaces. This makes step-cut diamonds more suited for those who appreciate elegance and clarity over sparkle.

Advantages of Step Cut Diamonds:
Clarity Visibility: Step cuts are perfect for diamonds with excellent clarity because they allow you to see the diamond’s interior more clearly. This cut tends to highlight a diamond’s cleanliness and colour.

Sophisticated and Timeless: The elegant, understated look of step-cut diamonds makes them a favourite choice for those who prefer a more classic and timeless design. They often lend themselves to vintage-style or art-deco designs.

Better for Larger Stones: Step cuts tend to work well with larger diamonds because they allow the stone’s size to be appreciated without excessive light dispersion, which can make smaller diamonds appear less impressive. The open facet structure in step cuts can give larger diamonds a cleaner and more sophisticated appearance.

Disadvantages of Step Cut Diamonds:
Less Sparkle: While step-cut diamonds still possess beauty and brilliance, they do not reflect light in the same way that brilliant-cut diamonds do. The less intense sparkle can make them less desirable for those who prefer the flashy brilliance associated with modern cuts.

Visibility of Inclusions: Step cuts can make internal inclusions or imperfections more visible due to the large, open facets. Therefore, diamonds with higher clarity are preferred for step-cut styles to avoid any noticeable flaws.

The step cut is a refined and elegant diamond cutting style that emphasises clarity and colour over intense sparkle. With its distinct rows of elongated facets running parallel to the girdle, step-cut diamonds (like the emerald and baguette cuts) offer a timeless aesthetic that appeals to those seeking sophistication and simplicity. This cut is particularly well-suited for larger diamonds and stones with high clarity, and while it may not produce the same level of sparkle as a brilliant cut, it offers a unique, understated beauty that is highly valued in vintage and classic jewellery designs.

July, 2017February, 2025

Symmetry

Symmetry in a diamond refers to the degree of alignment and uniformity in the shape and placement of its facets. It describes how well the facets of the diamond align with one another, creating a harmonious, balanced structure. High symmetry ensures that each facet is positioned correctly and consistently, contributing to the overall beauty, brilliance, and sparkle of the diamond.

Importance of Symmetry in Diamonds:
Light Reflection and Refraction: The primary reason symmetry is so crucial is because it directly impacts the light performance of the diamond. A diamond with imperfect symmetry will not reflect and refract light as efficiently as one with perfect symmetry. The facets are responsible for bouncing light throughout the diamond, and when they are aligned symmetrically, they allow light to be returned to the eye in a uniform and harmonious way, increasing the diamond’s brilliance and fire. Asymmetry, on the other hand, may cause the light to be dispersed unevenly, leading to a less vibrant or dull appearance.

Brilliance and Sparkle: Symmetry is one of the key contributors to a diamond’s brilliance (the return of white light) and scintillation (the flashes of colour and sparkle as the diamond moves). When the facets are well-aligned and symmetrical, they work together to reflect and direct light, producing more intense sparkle. For example, round brilliant-cut diamonds are famous for displaying hearts and arrows patterns (a symmetrical optical effect visible under magnification), which are a direct result of precise symmetry in the cut.

Consistency Across Facets: In well-cut diamonds, symmetry means that the size, shape, and placement of each facet are consistent, whether it’s in a round brilliant, emerald cut, or any other shape. In a round brilliant cut diamond, for example, all the upper and lower facets (including the star facets, bezel facets, and pavilion facets) should be of equal size and alignment to create a seamless and balanced look. Even minor deviations can affect the diamond’s overall visual appeal.

Impact of Symmetry on Diamond Grading:
Diamond Grading: The symmetry of a diamond is evaluated as part of the overall cut grade, which is one of the four Cs (Carat, Cut, Colour, and Clarity). Diamonds with perfect symmetry often receive higher grades, as their precise proportions enhance both aesthetic beauty and light performance. Symmetry is graded on a scale that can range from Excellent to Poor, depending on how accurately the facets align and match each other.

Perfect Symmetry: A diamond with perfect symmetry has facets that are so well-aligned that they create a balanced, flawless reflection of light. This is often seen in high-quality diamonds, where precision cutting is paramount.

Symmetry in Fancy Cuts: While symmetry is often most easily assessed in round brilliant cut diamonds, it is also important in other fancy cuts like the emerald cut, princess cut, or radiant cut. For example, in an emerald cut, symmetry can be seen in the parallel arrangement of the facets, and the alignment of corners should be perfect to achieve a clean, even look.

Hearts and Arrows:
In round brilliant cut diamonds, symmetry is so precise that it can create a distinct pattern known as hearts and arrows. When viewed under magnification, a well-cut round brilliant diamond will reveal a heart-shaped pattern on the bottom of the diamond (the pavilion) and arrow-shaped patterns on the top (the crown). These patterns are a clear indication of exceptional symmetry and contribute to the diamond’s perceived perfection.

Hearts and Arrows: The hearts and arrows pattern is highly prized in diamonds, particularly those cut to the highest standards of symmetry. It is a rare phenomenon that occurs only when the diamond’s facets are aligned so precisely that they reflect light in a perfect, symmetrical manner.
Symmetry in Other Cuts:
Symmetry is also vital in fancy-shaped diamonds (e.g., pear, oval, asscher, and radiant cuts). For instance:

In oval-cut diamonds, symmetry is judged by how well the curves of the diamond are evenly shaped and balanced.
In princess-cut diamonds, the symmetry of the corners and the alignment of facets is crucial to creating a visually appealing and well-proportioned diamond.

Symmetry is an essential factor that determines the overall beauty and performance of a diamond. It directly influences how the diamond interacts with light, impacting its brilliance, fire, and scintillation. Symmetrical diamonds are not only more visually appealing but also demonstrate higher cut quality, which is why symmetry is one of the main criteria in diamond grading. Whether it’s a round brilliant showing hearts and arrows or a fancy cut with perfectly aligned facets, symmetry plays a vital role in ensuring that a diamond sparkles to its fullest potential.

July, 2017February, 2025

Synthetic Diamond

A synthetic diamond (also known as a lab-grown diamond, man-made diamond, or cultured diamond) is a diamond that is created through artificial processes in a laboratory rather than being formed naturally over millions or billions of years in the Earth’s crust. Despite their man-made origins, synthetic diamonds have the same chemical composition, physical properties, and optical characteristics as natural diamonds, making them a true diamond in every sense. However, the main difference is that they are created in a controlled environment in a much shorter time frame, often just a few days or weeks.

How Synthetic Diamonds Are Made:
There are two primary methods used to produce synthetic diamonds:

High Pressure High Temperature (HPHT): The HPHT method simulates the intense pressure and temperature conditions that occur deep within the Earth, where natural diamonds form. In this process, carbon is subjected to pressures of around 1.5 million psi and temperatures of 1,500°C (2,732°F). The carbon is then placed in a chamber with a metal catalyst, which helps the carbon crystallise into diamond. The HPHT method is often used for producing gem-quality diamonds and is also used to create diamonds for industrial purposes.

Chemical Vapor Deposition (CVD): The CVD method involves using gaseous hydrocarbons (like methane) to create a plasma (an ionised gas) that breaks the bonds of the molecules in the gas, allowing the carbon atoms to slowly deposit layer by layer on a substrate (a small diamond seed). Over time, the carbon atoms arrange themselves into the crystal structure of a diamond. This process is carried out in a vacuum chamber at lower pressures and temperatures compared to HPHT. CVD diamonds can be grown to large sizes and are often used for high-quality gem diamonds as well as industrial applications.

Properties of Synthetic Diamonds:
Chemical Composition: Synthetic diamonds are composed of the same material as natural diamonds: pure carbon. The atoms of carbon are arranged in a specific crystal lattice structure, which gives diamonds their famous hardness and brilliance. Synthetic diamonds are made from high-purity carbon and undergo similar processes of crystallisation, resulting in diamonds with the same chemical bonds and rigid lattice structure as natural diamonds.

Hardness: Synthetic diamonds are just as hard as natural diamonds. They score 10 on the Mohs scale of hardness, the highest possible rating. This makes them incredibly durable and resistant to scratches, just like their natural counterparts.

Appearance: Lab-grown diamonds have the same optical properties as natural diamonds, including their brilliance, fire, and scintillation. This means they will sparkle and shine in the same way when exposed to light. Since they are chemically identical to natural diamonds, their appearance is indistinguishable to the naked eye. Advanced gemological testing is often required to differentiate between natural and synthetic diamonds.

Cost: One of the biggest differences between synthetic diamonds and natural diamonds is their price. Due to the shorter production time and technological advancements in the manufacturing process, synthetic diamonds typically cost significantly less than natural diamonds of the same size and quality. This price difference makes synthetic diamonds an attractive option for those seeking a diamond at a more affordable price point.

Environmental and Ethical Considerations:
Environmental Impact: Synthetic diamonds have a much lower environmental impact compared to natural diamonds. The mining of natural diamonds can be destructive to the environment, involving large-scale operations that disturb ecosystems and generate waste. In contrast, lab-grown diamonds have a much smaller carbon footprint, as they do not require the large-scale excavation of land or the energy-intensive processes associated with diamond mining.

Ethical Sourcing: Synthetic diamonds also offer a more ethical alternative to natural diamonds. The diamond mining industry has faced criticism over the years for issues related to human rights violations, including child labour and exploitation in conflict zones, known as “blood diamonds”. Synthetic diamonds, however, are produced in controlled laboratory settings where workers are paid fairly and the production process is transparent, making them a more ethical choice for those concerned with the origins of their jewellery.

Types of Synthetic Diamonds:
Gem-Quality Synthetic Diamonds: These diamonds are created for use in fine jewellery and have the same quality and appearance as natural diamonds. They can be cut into various shapes, including round, princess, emerald, oval, and more. Gem-quality synthetic diamonds are graded using the same criteria as natural diamonds, such as carat weight, colour, clarity, and cut.

Industrial Synthetic Diamonds: These diamonds are typically smaller, lower-quality diamonds that are used for industrial applications, such as cutting, grinding, and drilling. Industrial synthetic diamonds are produced in larger quantities and are not necessarily intended for use in jewellery. They are valued primarily for their hardness and durability, which makes them ideal for heavy-duty tools and machinery.

Distinguishing Between Synthetic and Natural Diamonds:
While synthetic diamonds are physically identical to natural diamonds, they can still be differentiated using advanced technology:

Inclusions: Synthetic diamonds may contain inclusions that are different from those found in natural diamonds. For example, synthetic diamonds grown using the CVD process often have distinctive inclusions, such as gas bubbles or metallic inclusions, which can be detected by a gemologist.
Growth Patterns: Under microscopic examination, the growth patterns of synthetic diamonds can be identified. HPHT diamonds, for instance, may display distinctive growth patterns in their crystal structure.
Spectroscopic Testing: Laboratory tests, such as infrared spectroscopy or ultraviolet-visible spectroscopy, can be used to determine whether a diamond is synthetic or natural.

Synthetic diamonds offer a cost-effective, ethical, and environmentally friendly alternative to natural diamonds. Created using advanced technology in a laboratory, these diamonds possess the same chemical structure and visual properties as their natural counterparts. Whether for fine jewellery or industrial uses, synthetic diamonds provide an option that caters to a growing market of consumers looking for diamonds at a lower price point, while still enjoying the beauty and durability of this remarkable gemstone.

July, 2017February, 2025

Single-Cut

A single-cut diamond refers to an old-style cut that features only 16 facets in total – 8 on the crown (the top portion of the diamond) and 8 on the pavilion (the lower portion). This style of diamond cutting is one of the earliest methods used in diamond cutting history and was prevalent before more advanced cuts like the brilliant cut became popular.

The single-cut diamonds were originally designed to make the most of the available diamond rough, often with the goal of enhancing the sparkle of small stones. The limited number of facets (compared to modern cuts) results in a simpler appearance, but they still display a degree of brilliance when well-cut.

Key Features of Single-Cut Diamonds:
Facets: The single-cut diamond typically has 16 facets – 8 on the crown and 8 on the pavilion, making it less complex than the round brilliant or emerald cut, which have far more facets.

Size and Sparkle: This style of cut is typically used for small diamonds. Despite the simpler facet structure, a well-cut single-cut diamond can still display sparkle, though it will not exhibit the intensity of light return seen in more modern cuts.

Historical Significance: The single cut was one of the first attempts at enhancing the natural sparkle of a diamond and was the preferred cut for small diamonds in vintage jewellery. It is still sometimes used today for very small diamonds (such as those used in mosaic or pavé settings), where a smaller, simpler cut is sufficient.

Modern Use: Although modern diamond cutting techniques now dominate, the single-cut remains relevant in certain instances, especially for tiny accent diamonds in vintage-inspired designs or budget-friendly pieces. This cut tends to be affordable due to the simplicity and fewer facets involved in the cutting process.

Appearance: The look of a single-cut diamond is generally less brilliant than a modern round brilliant cut, as it has fewer facets to interact with light. However, it still offers a certain charm, particularly in smaller sizes, where the increased facet count of larger stones may not be necessary.

Other Names:
The single-cut diamond is also referred to as an eight cut, which describes the eight facets on each side (crown and pavilion), emphasising its simplicity compared to the more complex, modern diamond cuts.

While not as commonly used for larger stones today, the single cut holds a place in history and is cherished in vintage and antique jewellery, often offering a nostalgic, traditional look for those seeking a more classic style.

July, 2017February, 2025

Star Facets

Star facets are the triangle-shaped facets that are located directly around the table facet of a round brilliant cut diamond. These facets are an essential component of the diamond’s overall faceting structure and play a crucial role in the diamond’s brilliance and light performance.

Key Characteristics of Star Facets:
Shape and Position: Star facets are triangular in shape, and they are placed above the girdle (the widest part of the diamond), surrounding the table facet, which is the large, flat top surface of the diamond. In a round brilliant cut diamond, there are typically 8 star facets in total – one on each side of the table facet, creating a visual pattern that can resemble a star when viewed from above.

Light Reflection and Brilliance: The main purpose of star facets is to enhance the brilliance of a diamond by reflecting light in various directions. As light enters a diamond and reflects off the facets, it produces the sparkle and scintillation for which diamonds are known. The star facets, along with the other facets in the round brilliant cut, help maximise the amount of light that is reflected back to the observer’s eye.

Arrangement in a Round Brilliant Cut: The round brilliant cut typically features 57 facets (or 58 if the culet is present), and the star facets are an integral part of this highly structured cut. They are strategically placed between the table facet and the upper girdle facets. Their purpose is to capture and reflect light from the top of the diamond, helping to create the sparkling effect.

Visual Effect: When viewed from above, the 8 star facets are positioned symmetrically around the table to form the shape of an 8-point star. This symmetry contributes to the overall aesthetic appeal of the round brilliant cut and plays a part in its popularity as one of the most sought-after diamond cuts.

Impact on Diamond’s Light Performance: The star facets are key contributors to a diamond’s light performance, including the creation of fire (the dispersion of light into its spectral colours) and brilliance (the return of white light). When cut well, star facets help maximise a diamond’s overall visual impact by ensuring the diamond sparkles intensely.

Role in Diamond Grading:
In diamond grading, star facets are evaluated as part of the overall cut quality. The precision of the cut and the symmetry of the facets contribute to the diamond’s grade in terms of how well it reflects light and sparkles. Well-executed star facets will help improve the overall cut grade of the diamond, as they are directly involved in achieving the maximum brilliance.

Star facets are an essential part of the round brilliant cut diamond, contributing to its signature brilliance, fire, and sparkle. Positioned around the table facet, these triangle-shaped facets create the appearance of a star and help to reflect light in all directions, making the diamond sparkle with incredible intensity. Their precision and symmetry are crucial to achieving the diamond’s full potential, and they play a major role in the overall beauty of a well-cut diamond.

July, 2017February, 2025

Scintillation

Scintillation refers to the sparkle or twinkle that a diamond exhibits as light reflects off its surface when it is in motion. This effect creates a series of quickly shifting flashes of light, which are particularly noticeable when the diamond is moved. The dynamic movement of the stone causes light to be reflected in different directions, producing a visually captivating and lively display of brightness and colour. Scintillation is one of the key visual characteristics that contributes to a diamond’s overall allure and desirability, alongside other factors such as brilliance and fire.

Key Features of Scintillation
Definition of Scintillation:

Scintillation is the rapid, sparkling flashes of light that appear as a diamond is moved in different directions. This effect is created by the way light interacts with the diamond’s facets. The shifting nature of the scintillation is often described as “twinkling,” and it’s most noticeable when the diamond is moved or rotated in the light.
How Scintillation Occurs:

When a diamond is illuminated, light enters through its table (the flat top surface), is reflected off the facets (the flat surfaces of the diamond), and exits through the crown. The facets, depending on their size, shape, and angle, cause light to bounce and reflect off the diamond in a multitude of directions.
As the diamond is moved, the angles of reflection change, and the light flashes in varying positions, creating the scintillation effect. The more facets a diamond has, the more reflections can occur, leading to more noticeable scintillation.
Factors Influencing Scintillation: Several factors impact the intensity and quality of scintillation in a diamond:

Quality of Polish:
The polish of a diamond affects the smoothness of its surface. A well-polished diamond will have a smoother surface, allowing light to reflect more easily off the facets, creating a more intense scintillation effect. Poor polish can cause surface irregularities, leading to light scattering in less predictable ways and reducing the overall sparkle.

Facet Arrangement:
The way the facets are arranged also plays a role in the movement of light across the surface of the diamond. Symmetrical arrangements of facets allow for more consistent and structured reflections, leading to enhanced scintillation. Diamonds with asymmetrical or poorly aligned facets may not reflect light as effectively, reducing the intensity and consistency of the sparkle.

Size and Shape of the Diamond:
The size and shape of the diamond also influence the degree of scintillation. Larger diamonds have more surface area, which can produce more flashes of light. Additionally, diamonds with complex facet arrangements (like the round brilliant cut) tend to exhibit more scintillation due to the numerous facets designed to reflect light in different directions. Fancy-shaped diamonds, such as princess cut, emerald cut, and asscher cut, may also display scintillation, but it is influenced by their specific facet configurations.

Cut Quality:
The overall cut quality of a diamond is one of the most significant factors influencing scintillation. Diamonds that are cut to ideal proportions (as determined by standards such as the GIA or DCLA) will produce more sparkle, as light will be reflected more efficiently through the facets. Poorly cut diamonds, even with high colour or clarity, may lack the desired scintillation due to the misalignment of their facets or improper depth and table size.

Scintillation vs. Brilliance vs. Fire:

While brilliance refers to the amount of white light that is reflected from the diamond, and fire refers to the dispersion of coloured light (such as flashes of red, blue, and yellow), scintillation is more closely related to how dynamic and moving the light appears when the diamond is rotated. Together, these three factors—brilliance, fire, and scintillation—create the visual appeal that makes diamonds so captivating.

Brilliance: The total amount of white light reflected from the diamond’s surface, which can be influenced by the cut, the angle of the facets, and the overall design of the diamond.

Fire: The dispersion of light into different colours as it travels through the diamond, creating rainbow-like flashes.

Scintillation: The movement of light across the surface of the diamond, seen as quick flashes or twinkling when the diamond is in motion.

Types of Diamonds and Scintillation:

Round Brilliant Cut Diamonds: Known for their exceptional scintillation, round brilliant diamonds have a highly structured and symmetrical facet arrangement designed to maximise light reflection. Their large number of facets and symmetrical cuts create dynamic scintillation, making them one of the most sparkling diamond cuts.
Princess Cut Diamonds: With a square or rectangular shape, princess cut diamonds also exhibit good scintillation, but the sparkle can differ due to their unique facet arrangements. The sharp corners of the princess cut can sometimes create brilliant flashes that differ from the round brilliant’s consistent twinkling.
Emerald Cut Diamonds: While the emerald cut is known for its clarity and elegant appearance, it doesn’t showcase as much scintillation as round or princess cuts. Instead, it focuses more on transparency and clarity of the diamond. However, it can still exhibit scintillation under certain lighting conditions, although it is less pronounced.
Cushion Cut Diamonds: The cushion cut diamond combines brilliance with fire, and its larger facets can create noticeable scintillation. The more modern cushion cuts with extra facets will tend to have more scintillation than the older, traditional ones.
Visual Impact of Scintillation:

Scintillation is what makes a diamond feel alive, contributing to its dynamic beauty. The ever-changing flashes of light draw the eye, making the diamond appear to sparkle and move with the slightest tilt or turn. This effect is especially noticeable in well-lit environments, where light reflects off the facets to create an irresistible twinkling effect.
Diamonds with high scintillation are often perceived as more lively and captivating, as the sparkle makes the stone appear dynamic and full of energy. Scintillation is a quality that people naturally associate with luxury, elegance, and timeless beauty.
The Role of Scintillation in Diamond Selection:

For those selecting a diamond, scintillation can be an important factor to consider, particularly if the buyer is looking for a diamond that will create an impactful visual presence. Diamonds with higher scintillation will tend to stand out in light and movement, making them excellent choices for people who want their diamonds to have a noticeable sparkle.
Brilliant cuts, such as the round brilliant, are often selected for their ability to exhibit maximum scintillation. However, other shapes, such as the princess cut or oval cut, can still provide plenty of sparkle, though the effect may be slightly different.

Scintillation is a key feature of a diamond’s visual appeal, referring to the dynamic sparkle that occurs when light is reflected off the diamond’s facets during movement. This shimmering effect is dependent on factors such as the quality of the polish, the arrangement of facets, and the cut quality of the diamond. Diamonds with excellent scintillation create a lively, twinkling effect that enhances their beauty, making them incredibly captivating and desirable. Whether in a round brilliant, princess, or cushion cut, scintillation remains one of the primary aspects that make diamonds so visually stunning and prized.