Category: Glossary

The diamond culet is the flat surface at the very bottom of the diamond, specifically at the pavilion’s tip. It plays a role in the diamond’s overall appearance, cut quality, and how it interacts with light.

Key Points about the Diamond Culet:
Location:

The culet is located at the very bottom of the diamond, at the pavilion, which is the lower portion of the diamond beneath the girdle.
It forms part of the cut and is essentially the small facet at the apex of the pavilion, where the diamond tapers to a point (in traditional cuts like round brilliant).
Function:

Purpose: The culet serves to prevent the diamond from being damaged during the cutting process. If the point of the pavilion were left unpolished or sharp, it could easily chip or break. The culet helps avoid this by giving the diamond a flat surface at the tip.
Light Interaction: The culet doesn’t significantly affect the light return or brilliance of the diamond, but its size and presence can influence the appearance of the diamond from the bottom.
Culet Size:

None: Some diamonds are cut without a culet at all, especially if the diamond has a sharp, pointed pavilion (this is often seen in high-quality round brilliant cuts). These diamonds may be labeled as “no culet” or “culet: none” in grading reports.
Small: A small culet is typically 0.1% to 0.3% of the diameter of the diamond. This is most common in diamonds cut for optimal brilliance.
Medium, Large, or Very Large: Larger culets are rare but can be found in older or antique diamonds, as well as some cushion or asscher cuts. Larger culets can sometimes give the diamond an unusual look and may reduce the diamond’s overall brilliance and desirability.
Impact on Diamond’s Appearance:

A larger culet may be visible from the top of the diamond, especially in diamonds with a larger table or shallow cut. It can detract from the diamond’s brilliance by allowing light to escape more easily.
A small culet or no culet at all is generally preferred in modern diamond cuts, as it maintains the maximum light performance and enhances the sparkle.
Culet and Clarity:

A large culet can sometimes be considered an inclusion when graded for clarity, as it may affect the overall symmetry of the diamond. However, a small or no culet typically doesn’t affect the diamond’s clarity.
The size and presence of the culet are typically noted in a diamond’s grading report, but it is not a major factor in the diamond’s clarity grade unless it affects the overall symmetry or appears as a significant visible feature.
Culet and Cut Quality:

While the culet doesn’t directly influence the light performance or brilliance, the proportions and symmetry of the cut, including the culet, are important for achieving an optimal cut grade.
Symmetry: A well-formed, symmetrical culet contributes to the diamond’s overall cut quality, enhancing its visual appeal.
Summary:
The diamond culet is the small flat facet at the tip of the diamond’s pavilion, designed to prevent damage during the cutting process.
Culet Size: It can be absent (no culet), small, medium, or large, with smaller culets generally preferred for better light return and brilliance.
Impact on Appearance: A larger culet may be visible from the top and can reduce the diamond’s sparkle. A small culet or no culet is preferred in modern cuts.
Clarity and Symmetry: The size of the culet can affect the diamond’s clarity and symmetry, but typically does not impact overall clarity unless it’s large or noticeably visible.

The diamond crown height percentage refers to the ratio of the height of the crown (the top portion of the diamond) relative to the total depth of the diamond. This percentage is a key factor in evaluating the cut quality of a diamond and has a direct impact on how well the diamond reflects light, which in turn affects its brilliance and fire.

Ideal Crown Height Percentage:
For a round brilliant cut diamond, the ideal crown height typically falls between 12% and 16% of the total depth of the diamond.
12% to 16% is considered the sweet spot because this range ensures that the crown is appropriately proportioned to maximize light return and optimize brilliance.
How to Calculate Crown Height Percentage:
The crown height percentage is calculated by dividing the height of the crown by the total depth of the diamond, then multiplying the result by 100.

Crown Height Percentage=(Total DepthCrown Height​)×100

Impact of Crown Height Percentage on Diamond Appearance:
Too Shallow: A crown height percentage that is too low (e.g., below 12%) can result in a diamond that looks flat and lacks brilliance. This is because light may escape through the sides of the diamond, reducing its sparkle.

Too Tall: A crown height percentage that is too high (e.g., above 16%) may make the diamond look overly deep or top-heavy, potentially reducing its overall brightness as light leaks out of the bottom, rather than returning through the table.

Ideal Proportion: Diamonds with a crown height percentage within the 12%-16% range tend to have the optimal balance of light reflection, maximizing both brilliance and fire. These diamonds typically appear vibrant and well-proportioned.

Crown Height and Other Proportions:
While crown height is crucial, it should not be considered in isolation. It works in conjunction with other cut proportions, such as:

Pavilion angle (the angle of the lower portion of the diamond)
Table size (the flat surface on top of the diamond)
Girdle thickness (the outermost edge of the diamond)
For the best light performance, all these proportions need to complement each other. A well-proportioned crown height enhances the overall cut quality and brilliance of the diamond, contributing to its desirability and value.

Summary:
Crown Height Percentage: The ratio of the crown height to the total depth of the diamond.
Ideal Range: The ideal crown height percentage for a round brilliant diamond is typically between 12% and 16%.
Impact on Brilliance: An ideal crown height percentage ensures maximum light return, producing a diamond with optimal sparkle and brilliance.

An internal crystal in a diamond refers to a type of inclusion (a naturally occurring characteristic inside the diamond). These crystals can be small mineral particles or other forms of inclusions trapped within the diamond during its formation deep within the Earth. Internal crystals are often used by gemologists to identify a diamond and can have an impact on the diamond’s appearance, clarity, and value.

Key Points about Internal Crystals in Diamonds:
Types of Internal Crystals:

Mineral Crystals: These are the most common type of internal crystals found in diamonds. They are usually small mineral particles that were trapped inside the diamond during its formation. These mineral crystals could be made of other minerals like garnet, peridot, or even graphite.
Diamond Crystals: Occasionally, diamonds may contain tiny crystals of diamond itself within them. These are rare but can appear as inclusions that look like tiny diamonds or clusters of diamond particles within the main diamond.
Other Inclusions: Other forms of inclusions, such as feathers, clouds, or blotches, might also contain internal crystals, but these are less common.
Impact on Clarity:

Clarity Grade: Internal crystals are considered inclusions, and they affect a diamond’s clarity grade. The presence of these inclusions can lower the clarity rating of a diamond, especially if the crystal is large, visible to the naked eye, or affects the overall appearance of the stone.
Diamonds are graded on clarity from Flawless (FL) to Included (I) based on the visibility and size of these internal characteristics. The larger and more noticeable the crystal, the more it can impact the clarity grade.
Visible Internal Crystals:

Inclusions Visibility: Some internal crystals may be visible to the naked eye, especially if they are large or located near the surface of the diamond. In other cases, they may be microscopic and only visible under magnification.
Location: The location of the internal crystal inside the diamond also plays a role in its visibility. If it’s near the surface, it may cause the diamond to have blemishes on the surface (as the crystal could potentially cause a chip or fracture if it’s not cut properly).
Internal Crystals and Diamond Value:

Negative Impact on Value: Larger, visible internal crystals generally decrease a diamond’s value, as they affect the clarity grade and overall appearance. The more inclusions there are inside the diamond, the lower the diamond’s clarity and value.
Exceptions: Sometimes, small internal crystals that are not visible to the naked eye may have little to no effect on the diamond’s appearance or value. In some cases, they might even add uniqueness to the diamond, especially if they are particularly small or unique in appearance.
Internal Crystals and Diamond Identification:

Unique Fingerprints: Every diamond contains its own unique combination of inclusions, including internal crystals, which makes diamonds identifiable. Gemologists use these characteristics, known as the diamond’s “fingerprint,” to confirm the diamond’s authenticity and traceability.
Laser Inscriptions: Some diamonds may have laser inscriptions on the girdle (the outer edge of the diamond) that record a unique identification number, which can be cross-referenced with a diamond’s internal characteristics and certificate.
Crystal Inclusions in Fancy Color Diamonds:

In fancy color diamonds, the presence of internal crystals can sometimes enhance or influence the overall color appearance of the diamond. For example, certain internal inclusions might give the diamond a different hue or intensity of color, particularly in diamonds with natural color variations like pink, blue, or green.
Crystal Inclusions and Durability:

The impact of internal crystals on a diamond’s durability depends on their size and location. While diamonds are incredibly strong and durable, large internal crystals near the surface may create weaknesses or make the diamond more prone to breaking or chipping.
Smaller internal crystals that are positioned away from the surface tend to have little impact on the diamond’s durability.
Summary:
Internal Crystal: An inclusion made up of a small mineral or diamond particle trapped inside the diamond during its formation.
Effect on Clarity: Internal crystals can lower a diamond’s clarity grade, especially if they are large or visible to the naked eye.
Identification: Internal crystals can act as a unique “fingerprint” for identifying a diamond.
Impact on Value: Larger, visible internal crystals can decrease the value of a diamond, though small, microscopic crystals may not have much impact.
Durability: Internal crystals near the surface can weaken the diamond and increase the risk of chipping.

A diamond crown refers to a piece of jewelry, often a tiara or headpiece, that is adorned with diamonds and designed to be worn on the head. It is typically associated with royalty, formal occasions, or beauty pageants. Diamond crowns can vary greatly in style, size, and design, but they generally feature diamonds as the central embellishment, showcasing their sparkle and brilliance.

Types of Diamond Crowns:
Royal Crowns:

Historically, royal crowns have been a symbol of power, authority, and sovereignty. These crowns, worn by kings, queens, and emperors, were often studded with large, valuable diamonds and other precious gemstones.
Crown jewels of various nations often feature diamonds, with some crowns containing famous diamonds, such as the Koh-i-Noor or the Cullinan Diamond.
Tiara Crowns:

Tiaras are a type of diamond crown that are typically worn at weddings, state functions, or formal events. They are less imposing than royal crowns but still offer a striking, elegant look. Tiaras may feature a combination of diamonds and other gemstones, arranged in intricate designs.
Popular among beauty pageants and high-society events, tiaras are often seen worn by those of aristocratic or royal lineage.
Wedding Crowns:

Some brides opt for a diamond crown or tiara as part of their wedding ensemble, adding a touch of glamour and sparkle. Wedding crowns are often designed to complement the bridal gown and can be customized to suit the bride’s personal style.
These crowns are typically more delicate and feminine, with diamonds arranged in a more subtle manner compared to royal crowns.
Decorative or Fashion Crowns:

Fashion crowns or decorative crowns are designed for ceremonial or decorative purposes and may be worn at costume events or themed parties. These crowns can be more creative, featuring diamonds alongside other elements like pearls, colored gemstones, and intricate metalwork.
Famous Diamond Crowns:
The Imperial State Crown (UK): Worn by the monarch during the State Opening of Parliament, this crown is encrusted with diamonds, including the Cullinan II Diamond, one of the largest cut diamonds in the world.

The Russian Imperial Crown: This historic crown is known for its diamonds, emeralds, and other gemstones. It was part of the Russian Crown Jewels and was worn by the czars during coronation ceremonies.

**The Koh-i-Noor Diamond Crown: This crown features the Koh-i-Noor diamond, which has a long and controversial history, and was once part of the British crown jewels.

Diamond Crown Design Elements:
Shape and Style: Diamond crowns may have different shapes, such as round, oval, or arched designs. Some are designed with a single row of diamonds, while others may have multiple tiers or intricate patterns.

Diamonds in Settings: Diamonds in a crown can be set in various ways, including prong settings, bezel settings, or pave settings. The setting influences how much light the diamonds reflect, contributing to their overall sparkle.

Other Gemstones: While diamonds are the focal point of most crowns, other gemstones such as emeralds, rubies, sapphires, and pearls are often incorporated for additional color and visual interest.

Symbolism of Diamond Crowns:
Royalty and Power: Diamond crowns symbolize power, wealth, and prestige. Historically, crowns were worn by those who held political or royal authority, and their adornment with diamonds signified both their wealth and divine right to rule.

Elegance and Celebration: In modern times, diamond crowns (often tiaras) symbolize elegance and beauty, and they are often worn at significant life events like weddings, pageants, and milestone celebrations.

Endurance and Purity: Diamonds are also symbolic of eternity and purity, which is why they are often used in crowns for weddings, representing the longevity and enduring nature of love.

Caring for a Diamond Crown:
Because of their value and intricate design, diamond crowns require careful maintenance:

Regular Cleaning: Like any piece of diamond jewelry, a diamond crown should be cleaned regularly to maintain its sparkle. A gentle solution of water and mild dish soap with a soft brush can be used.
Storage: Crowns should be stored carefully in a soft cloth or padded box to prevent scratching. If the crown is worn frequently, regular checks by a jeweler to ensure that the diamonds are secure are recommended.

The term “diamond crown angle” typically refers to the angle at which the crown of a diamond (the upper portion above the girdle) is cut. This is an important aspect of a diamond’s cut quality, as it influences the diamond’s brilliance and sparkle.

Key Points about the Diamond Crown Angle:
Crown:

The crown of a diamond is the top part of the diamond, extending from the girdle (the widest part of the diamond) to the table (the flat top surface).
The crown angle, or crown facet angle, is the angle formed between the plane of the table and the crown facets (the facets that make up the crown).
Crown Angle and Brilliance:

The crown angle plays a crucial role in how well a diamond reflects light. The angle affects how light enters and exits the diamond, impacting its brilliance (the white light reflected from the diamond) and fire (the dispersion of light into different colours).
A well-proportioned crown angle helps the diamond reflect light optimally, creating maximum brilliance and sparkle.
If the angle is too steep, the diamond can appear dark and lack brilliance, as light is directed away from the stone. Conversely, if the angle is too shallow, the diamond may lack depth and the light can escape through the bottom.
Ideal Crown Angle:

For a round brilliant diamond, the ideal crown angle typically ranges from 34° to 35°. Diamonds within this range tend to exhibit optimal brilliance and fire.
However, the crown angle must be considered in combination with other factors like the pavilion angle (the angle of the lower portion of the diamond) to achieve ideal proportions and light performance.
Ideal proportions typically result in a diamond that performs well in terms of both brilliance and fire, creating a visually pleasing sparkle.
Diamonds with Different Crown Angles:

Steep Crown Angle: A crown angle greater than 35° can lead to a steep crown, which might cause the diamond to appear darker or less sparkly due to light leakage.
Shallow Crown Angle: A crown angle lower than 34° can result in a shallow crown, which can make the diamond appear flat and may cause light to escape out of the sides of the stone, diminishing its brilliance.
Measuring the Crown Angle:

The crown angle can be measured using specialized tools and instruments in a gemological laboratory. It is often included in a diamond’s grading report (such as those provided by the GIA or DCLA), where the diamond’s cut quality is assessed.
Cut Proportions and Overall Performance:

The crown angle is part of the overall cut grade, which also considers other factors like table size, pavilion depth, and girdle thickness. These factors work together to determine the diamond’s overall brilliance and visual appeal.
A diamond with an excellent cut will have a crown angle that complements the pavilion angle, creating a balanced and well-proportioned stone that maximizes light performance.
How the Crown Angle Affects Diamond Quality:
A diamond’s cut quality is considered the most important factor in determining its overall appearance, often more important than its carat weight, colour, or clarity. A diamond with an optimal crown angle is more likely to have exceptional light performance, ensuring the diamond sparkles brilliantly.

In diamond grading reports, such as those from the DCLA (Diamond Certification Laboratory of Australia) or GIA (Gemological Institute of America), the crown angle is used to evaluate the diamond’s cut quality and assess how well it will reflect light.

Summary of Ideal Crown Angle:
Round Brilliant Cut: Ideal crown angle is typically between 34° and 35° for maximum brilliance.
The crown angle works in conjunction with other factors, like the pavilion angle, to influence the diamond’s overall light performance.
If you’re considering purchasing a diamond, the crown angle is a crucial factor to keep in mind when evaluating the overall cut quality, as it directly affects how much sparkle and brilliance the diamond will exhibit.

The crown height of a diamond refers to the vertical measurement of the crown portion of the diamond, which is the area above the girdle (the widest part of the diamond). It is one of the key proportions that affects a diamond’s overall cut quality and visual appearance. The crown height plays a significant role in how well a diamond reflects light and how its sparkle is perceived.

Key Points About Diamond Crown Height:
Crown Height and Overall Cut:

The crown height is an important part of a diamond’s cut proportions, which determine how well the diamond will perform in terms of brilliance, fire, and scintillation.
The height of the crown is usually expressed as a percentage of the overall depth of the diamond. The depth is the total height of the diamond from the culet (bottom point) to the table (top flat surface).
Crown Height Proportions:

For a round brilliant diamond, the ideal crown height is typically between 12% and 16% of the total depth.
A crown height that is too shallow can cause the diamond to appear flat, as light may escape from the sides, reducing its brilliance and sparkle.
A crown that is too tall can make the diamond appear top-heavy, and it might lead to light leakage from the bottom of the diamond, affecting its overall light performance.
Crown Height and Brilliance:

The crown height affects the angle of the crown facets and, consequently, the way light enters and exits the diamond. Proper crown height ensures that light is reflected and refracted optimally within the stone, creating the sparkle and brilliance diamonds are known for.
When the crown height is proportioned correctly, it maximizes light return, ensuring that the diamond exhibits bright flashes of light and vibrant colours (fire).
Impact of Crown Height on Visual Appearance:

Shallow Crown Height: A crown that is too shallow may cause the diamond to look less vibrant and may reduce its overall brightness. Light can escape from the sides, diminishing the diamond’s sparkle.
Tall Crown Height: A crown that is too tall can make the diamond look overly deep or heavy, which can reduce the amount of light returning through the top of the diamond, leading to a darker appearance.
Relationship with Pavilion Angle:

The crown height is often considered alongside the pavilion angle (the angle of the lower portion of the diamond) to determine the diamond’s overall light performance. The crown and pavilion work together to reflect light properly inside the diamond, and the proportions of these angles must complement each other for optimal results.
Crown Height in Grading:

When diamonds are graded by gemological laboratories like GIA or DCLA, the crown height is taken into consideration as part of the overall cut grade. A well-proportioned crown height helps achieve a grade of Excellent or Ideal in terms of cut quality, which is a critical factor in a diamond’s value and appearance.
Ideal Crown Height:

For a round brilliant cut, an ideal crown height typically falls between 12% and 16% of the total diamond depth.
This range ensures that the crown is tall enough to allow proper light reflection, but not so tall that it causes light leakage or reduces overall brightness.
Summary of Diamond Crown Height:
Crown Height: The vertical measurement from the girdle to the table of the diamond.
Ideal Proportion: For round brilliant diamonds, the crown height is ideally between 12% and 16% of the diamond’s total depth.
Impact on Light Performance: A properly proportioned crown height ensures the diamond reflects light optimally, producing maximum brilliance and sparkle.

Diamond Colour is one of the most important factors in determining a diamond’s quality and value. It refers to the absence of colour in a diamond, with diamonds being graded on a scale that ranges from colourless to light yellow or brown. The more colourless a diamond is, the higher its value.

Diamond Colour Grading:
The most common diamond colour grading scale is the GIA (Gemological Institute of America) scale, which is used by most gemological labs, including the DCLA (Diamond Certification Laboratory of Australia).

On the GIA scale, diamonds are graded from D to Z, with D being colourless and Z being diamonds with noticeable colour.

D – F (Colourless to Near Colourless):

D: Completely colourless, the highest grade. These diamonds are rare and extremely valuable.
E and F: Near colourless, with only slight traces of colour detectable under magnification. These diamonds still appear colourless to the naked eye and are highly valued.
G – J (Near Colourless):

These diamonds are still near colourless and typically look white to the naked eye. However, when compared to diamonds in the D-F range, there may be a very subtle hint of colour.
G: Near colourless, slightly less valuable than F but still excellent in appearance.
H: Slightly tinted, but appears mostly white to the naked eye.
I and J: Noticeably tinted, but still often appear white in settings that complement the diamond’s colour.
K – M (Faint Yellow or Brown):

Diamonds in this range show faint yellow or brown tint, which becomes more noticeable as the grade progresses.
N – Z (Light Yellow or Brown):

These diamonds show a more noticeable colour (yellow or brown), and while still diamonds, they are typically considered less valuable than those in the D-J range.
DCLA and the Diamond Colour Grading Process:
The DCLA (Diamond Certification Laboratory of Australia) is one of the leading gemological laboratories in Australia that provides reliable and accurate diamond certification, including diamond colour grading. DCLA follows internationally recognized standards for grading diamond colour, similar to the GIA scale.

As part of their grading process, DCLA uses an official master set of diamonds to compare the diamond in question and determine its exact colour grade. This ensures that the grading is precise and consistent with global standards. The DCLA master set is made up of a range of diamonds, each representing one of the standard colour grades, and serves as a reference tool for accurate grading.

DCLA’s Official Master Set for Colour Grading:
The DCLA master set consists of diamonds of known colour that act as the benchmark for evaluating the colour of other diamonds.
These reference diamonds are carefully selected to represent each colour grade, from D (colourless) to Z (light yellow or brown). When a diamond is submitted for certification, DCLA compares it to this master set to determine its accurate colour grade.
DCLA’s commitment to precision ensures that their colour grading is consistent, and their grading system is recognized by jewelers, consumers, and industry professionals.
Importance of Colour in Diamond Valuation:
Colourless diamonds (D-F grades) are the rarest and typically the most expensive because they allow for the most reflection of light and therefore exhibit the most brilliance and fire.
Near colourless diamonds (G-J grades) offer excellent value for those looking for a balance of quality and price. They are often indistinguishable from the higher grades without close inspection.
Diamonds with faint to noticeable yellow or brown tints (K-Z grades) tend to be more affordable but may lack the brilliance of the higher grades due to the presence of colour.
Why Choose a Diamond with a DCLA Certification?
Transparency and Trust: DCLA provides accurate, reliable colour grading based on internationally accepted standards, which ensures that the buyer knows exactly what they are purchasing.
Consistency: The DCLA Master Set ensures that diamonds are evaluated based on consistent criteria, allowing for a reliable comparison of diamonds and ensuring that the colour grading is trustworthy.
Security: Diamonds certified by DCLA are marked with a unique laser inscription that helps identify and authenticate the diamond, adding another layer of security for buyers.
How to Choose the Right Diamond Colour:
If brilliance is your top priority, opt for a D-F grade diamond.
If you are looking for a better value without sacrificing much on appearance, G-H grade diamonds are a great choice.
For larger diamonds or those in settings where the diamond is not viewed up close, I-J diamonds can offer good value for a larger size.