Glossary – Page 3 – The Diamond Certification Laboratory of Australia (DCLA)

July, 2017February, 2025

Shape

Name for the basic outline of a polished diamond

In the context of diamonds, shape refers to the basic outline or form of a polished diamond, which is distinct from its cut (which pertains to the diamond’s facets, proportions, and overall craftsmanship). The shape is the fundamental, overall geometry of the diamond, determining its appearance and how it interacts with light. The shape of a diamond is typically selected based on personal preference, aesthetic taste, and desired brilliance, as different shapes have different effects on the way a diamond reflects light and sparkles.

Types of Diamond Shapes
There are several common diamond shapes, each with unique characteristics, and they vary in terms of their appearance, the way they reflect light, and their overall style. Below are some of the most popular diamond shapes:

Round:

The round shape is the most popular and traditional diamond shape, known for its exceptional brilliance and sparkle. It has a circular outline and is cut with 57 or 58 facets, including the table, crown, pavilion, and girdle. This shape maximises light reflection, making it the most sought-after shape for engagement rings and other jewellery.
The round shape is also known as the round brilliant cut, which is designed to achieve the highest level of brilliance and scintillation, making it the benchmark for diamond cutting.
Princess:

The princess shape is a square or rectangular diamond with pointed corners. It is the second most popular diamond shape after the round shape and is prized for its sharp, modern appearance. Princess cut diamonds have a brilliant faceting style, offering excellent sparkle. This shape is often selected for engagement rings and other jewellery due to its versatile and elegant appearance.
This shape is known for its clean lines, and it’s often favoured by those who want the brilliance of a round diamond but prefer a more angular look.
Emerald:

The emerald shape is a rectangular diamond with cut corners and a step-cut faceting style. Unlike the brilliant cuts, emerald cut diamonds are more about clarity and the stone’s internal characteristics, showcasing the diamond’s clarity through large, open facets.
The emerald shape is known for its elegance, producing a sleek and sophisticated look. It is particularly suited for those who appreciate a vintage style or want a more subtle, understated sparkle compared to the brilliance of other cuts.
Cushion:

The cushion shape is a square or rectangular diamond with rounded corners, giving it a pillow-like appearance. This shape combines features of both the round brilliant and emerald cut, offering a balance of brilliance and clarity.
The cushion shape has a romantic, vintage appeal and is known for its soft, gentle curves. This shape has become increasingly popular in recent years, especially in antique-style jewellery.
Oval:

The oval shape is an elongated round diamond, offering the same brilliance as a round diamond but with an elongated, oval outline. This shape creates the illusion of a larger stone due to its elongated shape and is often chosen for its ability to make fingers appear more slender.
Oval diamonds are known for their classic elegance and sparkling appearance. The elongated form gives a sense of modernity, and it works well in many jewellery settings, particularly for engagement rings.
Marquise:

The marquise shape is a football-like or boat-shaped diamond, with pointed ends and a long, elongated outline. This shape is known for creating the illusion of length and size, making it appear larger than other shapes of the same carat weight.
Marquise diamonds are ideal for creating a bold, dramatic look and are often used in statement pieces or vintage-inspired designs.
Pear:

The pear shape is a combination of round and marquise cuts, with one pointed end and one rounded end, resembling a teardrop. This shape has a soft, elegant look and is often seen in pendants, earrings, and engagement rings.
The pear shape is known for its flattering effect on the hand or neck, as its elongated shape can make the fingers or neckline appear more slender. It also offers a unique balance of brilliance and elegance.
Asscher:

The asscher shape is a square version of the emerald cut, with cut corners and a distinctive step-cut faceting. This shape has a vintage appeal, often associated with the early 20th century and the art deco period.
The asscher shape is known for its regal, sophisticated look and clarity, emphasising the diamond’s natural beauty and internal characteristics. It’s a great choice for those who enjoy vintage or retro styles.
Radiant:

The radiant shape is a square or rectangular diamond with cut corners, combining the brilliance of a round cut with the elegance of an emerald cut. The facets of a radiant diamond are typically more brilliant, giving the stone a striking sparkle while retaining its structured outline.
Radiant diamonds are popular for their modern appeal and versatility, working well in many types of jewellery, from engagement rings to statement necklaces.
Heart:

The heart shape is a romantic, symbolic diamond shape, resembling a heart. It’s a modified brilliant cut, and it’s often selected for engagement rings and valentine’s jewellery due to its emotional significance.
Heart-shaped diamonds combine both brilliance and emotional appeal, and they are often used in pendants, rings, and earrings for special occasions.
Factors Influencing Diamond Shape Selection
When choosing a diamond shape, several factors should be considered:

Personal Taste: The aesthetic preference of the buyer plays a crucial role in selecting the shape. Some may prefer the classic brilliance of the round shape, while others may gravitate towards the elegance of the emerald or the romance of the heart.

Brilliance: Different shapes have varying levels of brilliance. Round diamonds generally offer the highest level of brilliance, while step-cut diamonds (like emerald and asscher) may offer less sparkle but more emphasis on clarity.

Finger Shape and Size: Some diamond shapes, like the oval and marquise, can make fingers appear longer and slender, while other shapes, like cushion or round, may have a more balanced look.

Diamond Setting: The shape of the diamond affects the type of setting it can be used with. Round diamonds fit most settings, but fancy-shaped diamonds, like pear or heart, may require more custom settings to highlight their unique outlines.

Size Appearance: Some diamond shapes, like marquise and pear, can create the illusion of a larger diamond, which may be preferred for those looking for a bigger appearance without increasing carat weight.

The shape of a diamond is a fundamental factor in its overall appearance and appeal. Each shape offers its own unique style, brilliance, and aesthetic qualities, allowing buyers to select the diamond that best reflects their personal tastes, lifestyle, and the intended jewellery setting. Whether opting for the timeless round or the elegant emerald, each shape offers something special, making it an essential element in choosing the perfect diamond.

July, 2017February, 2025

Simulant

A diamond simulant is any material that is designed to mimic the appearance of a diamond but is not a natural diamond or a synthetic diamond. Simulants can have a similar look, including sparkle, clarity, and colour to diamonds, but they are made from entirely different materials. These materials are often chosen because they are affordable alternatives that provide a diamond-like aesthetic without the high price tag.

Types of Diamond Simulants
Several materials are commonly used as diamond simulants, each offering different levels of resemblance to diamonds in terms of appearance, durability, and cost. Some of the most well-known diamond simulants include:

Cubic Zirconia (CZ):

Cubic zirconia is one of the most popular and widely recognised diamond simulants. It is a man-made gemstone made from zirconium dioxide, which is heat-treated to produce a material with a brilliant appearance.
While cubic zirconia can look very similar to a diamond at first glance, it has a lower hardness (8-8.5 on the Mohs scale compared to diamond’s 10) and a softer, more brittle structure, making it more prone to scratching over time.
Cubic zirconia is often used in cost-effective jewellery and can be found in a wide range of shapes, sizes, and colours. While it may sparkle brightly, it lacks the brilliance and fire that diamonds possess, and its optical properties are different from those of a true diamond.
Moissanite:

Moissanite is a naturally occurring mineral (silicon carbide) that is often synthetically produced for use in jewellery. It is considered one of the best diamond simulants due to its exceptional brilliance and fire (the ability to reflect colourful flashes of light).
Moissanite is harder than cubic zirconia, ranking 9.25 on the Mohs scale, making it more resistant to scratching and wear. It is very difficult to distinguish from a diamond without magnification or expert testing.
The key difference between moissanite and diamonds is that moissanite has more rainbow-like flashes in the light, while diamonds tend to exhibit a more white sparkle.
Glass:

Glass is a less expensive and less durable material that is sometimes used as a diamond simulant. Lead glass is sometimes treated to look like a diamond, but it lacks the hardness and optical brilliance of other simulants. Glass can easily be scratched or chipped, and it will show more signs of wear than other simulants.
Glass can have a shiny appearance and can be cut to mimic a diamond shape, but its sparkle is far less intense than that of a diamond, and its light dispersion (fire) is almost nonexistent.
White Sapphire:

White sapphire is a natural gemstone that is used as a diamond alternative. While it is not a simulant in the traditional sense, it is often used in jewellery as a substitute for diamonds. White sapphires are harder than cubic zirconia (9 on the Mohs scale), and although they are durable, they do not exhibit the same level of brilliance as diamonds.
The luster of white sapphire is different from diamonds, and it may appear a bit more dull or flat compared to the dazzling sparkle of a true diamond. However, it can be an attractive and more affordable alternative.
Zircon:

Zircon is a naturally occurring gemstone that can be clear or colourless, resembling a diamond. However, zircon has a lower hardness (7.5 on the Mohs scale) than both diamonds and moissanite, making it prone to wear and scratching.
It is also optically different from a diamond, exhibiting more fire (the colourful flashes of light), but its brilliance does not match the diamond’s. Despite its brilliance, zircon’s fragility and lack of long-term durability make it less ideal as a diamond simulant.
White Topaz:

Topaz is another natural gemstone that can be colourless and used as a diamond simulant. White topaz is often treated to enhance its colour and appearance, and it has a brilliant appearance under light.
However, topaz is softer than diamonds, ranking 8 on the Mohs scale, and while it is still durable, it is more prone to scratching and clouding over time. The sparkle of white topaz is not as intense or dynamic as that of a diamond.
Differences Between Simulants and Diamonds
While diamond simulants may appear similar to diamonds in some ways, there are several key differences between them and a natural or synthetic diamond:

Hardness:

One of the most significant differences is the hardness of the material. Diamonds are the hardest natural substance on Earth (10 on the Mohs scale), which gives them their superior durability and scratch resistance. Simulants like cubic zirconia, moissanite, and glass are much softer and can become scratched and dull over time.
Brilliance:

Brilliance refers to how a diamond reflects white light, creating a sparkle that is highly prized in diamonds. While many simulants, especially moissanite, can have high levels of sparkle, they lack the unique dispersion of light found in diamonds, resulting in a different overall appearance. For example, moissanite has a more rainbow-like sparkle, while diamonds generally exhibit more white brilliance.
Fire:

Fire is the dispersion of light into its spectral colours. While moissanite and cubic zirconia can exhibit fire, the type and amount of fire in a diamond are unique and contribute to its iconic look. Cubic zirconia and glass have less fire, and their dispersion can be unnatural, making them easily distinguishable from real diamonds.
Price:

The primary attraction of simulants is their affordability. While natural diamonds can be extremely expensive due to their rarity and the labour-intensive processes of mining and cutting, simulants are far more budget-friendly. Moissanite and cubic zirconia, for example, are often used as alternatives in engagement rings and other jewellery for those seeking the look of a diamond without the cost.
Weight:

While simulants may appear similar to diamonds, they often weigh more than diamonds of the same size. For example, cubic zirconia and moissanite tend to be denser than diamonds, so a simulant of the same size will likely weigh more than a diamond of the same dimensions. This can be noticeable when comparing the weight of a stone and can help distinguish a simulant from a diamond.

Diamond simulants offer an attractive, affordable alternative to natural diamonds, especially for those seeking a diamond-like appearance without the high cost. While they may mimic the sparkle and shine of diamonds, they lack the durability, hardness, and intrinsic qualities that make diamonds unique. Whether choosing a simulant for an engagement ring or as an accessory, it’s important to understand the differences in appearance, longevity, and value when selecting the right material for your jewellery.

July, 2017February, 2025

Rough Diamond

A rough diamond is a diamond in its natural state, exactly as it is found deep within the Earth. It has not yet undergone any form of cutting, polishing, or alteration. Rough diamonds are typically irregular in shape, with a variety of textures, colours, and surface conditions, ranging from clear and transparent to opaque and coloured.

These diamonds are generally discovered in kimberlite pipes (volcanic formations) or alluvial deposits (water-worn areas), and they are extracted through a process of mining. Once found, rough diamonds are carefully sorted and graded based on their size, shape, colour, and clarity before they are sent to gem cutters for transformation into polished stones.

Key Characteristics of Rough Diamonds
Shape:

Rough diamonds are typically irregular, with shapes that can range from octahedral (two pyramidal shapes joined together) to dodecahedral (a 12-sided form). These shapes are determined by the crystal structure of the diamond and can vary widely.
The rough shape is not intended for jewellery, and the gem cutters will plan how to cut the stone based on its natural geometry to maximise yield and minimise waste.
Colour:

Rough diamonds can appear in a wide range of colours, from colourless and transparent to shades of yellow, brown, or even rare colours such as blue, green, or pink.
The final colour of the diamond will depend on its internal structure and any trace elements present in the rough material. Some rough diamonds are even tinted due to the presence of minerals or impurities.
Clarity:

In their natural form, rough diamonds may have a variety of inclusions and blemishes, such as tiny air bubbles or mineral inclusions trapped within the crystal. These internal flaws are often visible to the naked eye or under magnification, though they can be reduced or eliminated during the cutting and polishing processes.
Size:

Rough diamonds vary greatly in size, from small pebbles to large stones weighing several carats. Larger rough diamonds are often considered more valuable, especially if they possess good colour and clarity, as they can be cut into high-quality finished diamonds.
The Journey of a Rough Diamond
Extraction:

Rough diamonds are mined from the Earth, typically through open-pit mining, underground mining, or alluvial mining (searching for diamonds in riverbeds or coastal regions). Mining companies extract the rough stones from kimberlite pipes or riverbeds, often using advanced technology to locate diamond deposits deep underground.
Sorting and Grading:

Once extracted, rough diamonds are sorted based on their size, colour, clarity, and shape. Each diamond is examined to determine its potential for cutting and polishing. Some rough diamonds are too flawed or small to be cut into gem-quality stones and may be used for industrial purposes instead.
The DCLA (Diamond Certification Laboratory of Australia) offers rough diamond services to help classify and grade rough diamonds. They use their expertise to evaluate the quality of rough diamonds and assist in planning the best course of action for cutting and polishing.
Cutting and Polishing:

After sorting, the rough diamond is sent to skilled gem cutters, who use advanced techniques and tools to transform the stone into its finished form. The cutting process involves careful planning to maximise the yield (the amount of diamond produced from the rough stone) while aiming to enhance the diamond’s brilliance, fire, and overall appearance.
The diamond may be cut into a variety of shapes, such as round, emerald, princess, or cushion, depending on the rough stone’s shape and quality.
Grading:

Once the diamond is cut and polished, it is then graded according to the 4 Cs – Carat, Colour, Clarity, and Cut. This grade determines the diamond’s final value, and certificates from recognised laboratories such as DCLA are used to authenticate the quality of the diamond.
Uses of Rough Diamonds
Gem-quality Diamonds:

The primary use of rough diamonds is for gemstone production, where they are cut and polished into diamonds for use in engagement rings, earrings, necklaces, and other high-end jewellery.
Industrial Diamonds:

Some rough diamonds, particularly those with significant imperfections, are not suitable for use in jewellery. These diamonds are used for industrial purposes, where their hardness is highly valued. Industrial diamonds are employed in applications such as cutting, grinding, drilling, and polishing, where the diamond’s extreme hardness makes it ideal for cutting or shaping other materials.

The rough diamond is the very first step in the life cycle of a diamond. Found in the earth in its natural form, it is then extracted, sorted, and carefully crafted into the sparkling gemstones that are valued in fine jewellery. Due to their rarity and the complexity of their transformation, rough diamonds represent both the mystery of nature and the skill of the craftsmen who shape them into stunning finished products.

July, 2017February, 2025

Round Brilliant Cut

The Round Brilliant Cut is by far the most popular and widely recognised diamond cut, known for its ability to showcase a diamond’s brilliance, fire, and scintillation. It is designed to maximise the diamond’s reflective qualities and ensure that the stone sparkles to its fullest potential. The cut is characterised by its circular outline and cone-shaped pavilion, with a set number of facets that are precisely arranged to enhance the light performance of the diamond.

Key Features of the Round Brilliant Cut
Shape and Outline:

As the name suggests, the round brilliant cut is defined by its circular shape, which makes it instantly recognisable. This symmetrical shape enhances the light return, which is one of the key factors that contributes to the diamond’s brilliance. The round shape also provides a classic aesthetic, making it a timeless choice for engagement rings and other fine jewellery.
Facets:

The standard round brilliant cut typically has 57 facets, though some stones may have 58 facets if the culet (the small flat facet at the bottom of the diamond) is also included. These facets are carefully cut to reflect and refract light, creating the characteristic sparkle and fire that makes the round brilliant cut so desirable.
The facets of a round brilliant diamond are divided into three main sections: the crown, girdle, and pavilion:
Crown: The upper portion of the diamond, which includes the table (the flat top surface) and the facets that radiate from it.
Pavilion: The lower portion, which is cone-shaped and holds the majority of the diamond’s facets.
Girdle: The thin band around the diamond that separates the crown from the pavilion.
Brilliance, Fire, and Scintillation:

The brilliance of a round brilliant cut diamond refers to its white light reflection, or how much light the diamond returns to the eye. The angles and arrangement of the facets are designed to allow light to enter through the table, reflect off the internal surfaces, and return through the top of the diamond, creating that dazzling sparkle.
Fire refers to the flashes of coloured light that appear as the diamond moves. The number of facets in a round brilliant cut maximises the dispersion of light, creating vibrant flashes of red, blue, and yellow as the stone is rotated.
Scintillation is the term for the sparkle or twinkle of the diamond as it moves. A round brilliant cut diamond will exhibit high scintillation, meaning that it produces continuous flashes of light with every slight motion.
Cut Quality:

The cut quality of a round brilliant diamond is one of the most important factors influencing its overall beauty. The proportions of the diamond, including the table size, crown angle, pavilion depth, and girdle thickness, all play a crucial role in how well the diamond performs with light.
A well-cut diamond will have a perfect balance between brilliance, fire, and scintillation, with all the facets working together to maximise the diamond’s light return.
Diamonds with poor proportions will leak light, reducing the brilliance and fire of the stone, and making the diamond appear duller.
Round Brilliant Cut vs Other Cuts
The round brilliant cut is the most commonly chosen diamond shape, largely because it offers the best overall light performance. However, there are other shapes and cuts, each with their own appeal:

Cut Shape Facets Light Performance Appeal
Round Brilliant Circular 57 or 58 Exceptional brilliance, fire, scintillation Timeless, classic, maximum sparkle, highly popular
Princess Cut Square or Rectangular 57 Excellent brilliance, good scintillation Modern, sharp, distinctive, highly popular
Emerald Cut Rectangular 58 Moderate brilliance, strong clarity and transparency Elegant, sophisticated, highlights clarity
Cushion Cut Square with rounded corners 58 Good brilliance, antique-like appeal Romantic, vintage-inspired, soft sparkle
Oval Cut Oval 58 Similar to round, slightly elongated brilliance Unique, elegant, elongates the finger
Asscher Cut Square 58 Exceptional clarity, vintage look Art Deco style, striking clarity, bold aesthetic
Marquise Cut Boat-shaped 58 High brilliance, elongates appearance Dramatic, elegant, optimises carat weight
Advantages of the Round Brilliant Cut
Maximum Brilliance:

The round brilliant cut is specifically designed to maximise the brilliance of a diamond. The precise facet arrangement and angles ensure that the diamond performs optimally in terms of light reflection and refraction, resulting in a highly sparkling stone.
Timeless and Classic:

The round brilliant cut is a timeless design, and its classic appeal makes it one of the most popular choices for engagement rings and other fine jewellery. Its symmetrical shape is universally appealing, and it remains a symbol of elegance and refinement.
Versatility:

A round brilliant cut diamond can complement a wide variety of settings, from solitaire rings to halo settings or more intricate designs. The shape’s versatility means it suits both traditional and modern jewellery styles, making it a versatile choice for all types of jewellery.
Resale Value:

Round brilliant cut diamonds tend to hold their value well in the market. Due to their popularity and high demand, they are often considered a good investment choice, with strong resale value.
Considerations When Choosing a Round Brilliant Cut
Cut Quality:

The cut of a round brilliant diamond is one of the most important factors in determining its overall appearance. It’s essential to consider the diamond’s proportions, as a well-cut stone will showcase the best light performance. Always ensure that the diamond has been graded by a reputable lab, such as the GIA or DCLA, to ensure the cut is of high quality.
Budget:

Round brilliant cut diamonds are often priced at a premium due to their popularity and demand. While they offer exceptional beauty, it’s important to set a budget that aligns with your preferences and financial considerations. Smaller diamonds or diamonds with lower colour or clarity grades may be more affordable, while larger, higher-quality stones will command a higher price.
Carat Size:

The size of the round brilliant cut diamond also impacts its value. Larger stones typically cost more, and their brilliance is even more pronounced due to the increased surface area. However, even smaller round brilliant diamonds can deliver incredible sparkle and beauty when cut well.

The round brilliant cut remains the most popular and sought-after diamond shape due to its exceptional brilliance, sparkle, and timeless appeal. Its carefully planned facet arrangement ensures optimal light performance, creating a diamond that dazzles with every movement. Whether as an engagement ring, a pendant, or earrings, the round brilliant cut continues to captivate and delight, making it the perfect choice for anyone seeking a diamond with unmatched brilliance and elegance.

July, 2017February, 2025

Saturation

Intensity and purity of colour in a diamond

Saturation refers to the intensity and purity of colour within a diamond. It is a key factor in determining the overall colour grade of a diamond, alongside hue (the type of colour) and tone (the lightness or darkness of the colour). In diamonds, the more vivid and intense the colour, the higher the saturation level. This characteristic significantly influences the diamond’s value, with higher saturation diamonds generally being more desirable and commanding higher prices.

Understanding Diamond Saturation
Definition of Saturation:

Saturation measures the strength or richness of a diamond’s colour. It indicates how much of the diamond’s colour is concentrated and how pure that colour is, free from any other modifying hues. A highly saturated diamond will have a more intense, pure, and vibrant colour, whereas a diamond with low saturation will appear more faint or washed out, with a less pronounced colour.
Saturation Scale:

In the context of diamond grading, saturation is often assessed on a scale that ranges from faint to vivid or intense, depending on the type of diamond. The grading system for saturation is especially used when grading fancy coloured diamonds, which exhibit noticeable colours beyond the standard white or colourless diamonds. The scale typically includes the following categories:
Faint: Very little colour is present, and the diamond appears mostly colourless.
Light: A faint hint of colour can be seen, but it is still relatively subtle.
Fancy Light: A more noticeable colour, but still not as strong or vibrant as higher categories.
Fancy: A diamond that exhibits a noticeable, good-quality colour with moderate intensity.
Fancy Intense: A deep, saturated colour that appears vivid but may still allow some lightness or tone variations.
Fancy Vivid: The highest level of saturation, where the colour is rich, deep, and incredibly vibrant, creating a visually striking effect.
Impact of Saturation on Diamond Value:

Saturation plays a significant role in determining the value of fancy coloured diamonds. Generally, the greater the saturation, the more valuable the diamond. A diamond with higher saturation will often appear more striking and will usually be priced higher than a similarly graded diamond with lower saturation, assuming all other factors are equal. This is because more intense and vivid colours are rarer and more visually appealing.
For example, a fancy vivid blue diamond would typically be worth significantly more than a fancy light blue diamond, due to the difference in the intensity of colour.
How Saturation Affects the Appearance of Coloured Diamonds:

The saturation of a coloured diamond will directly influence how the diamond appears to the naked eye. For example:
A fancy vivid pink diamond will appear vibrant, rich, and highly saturated, showing a pure pink colour.
A light yellow diamond may have a subtle, pale yellow tint, whereas a vivid yellow diamond will have a much stronger and deeper yellow hue.
Blue diamonds that exhibit high saturation will have a deep, rich blue that catches light and appears strikingly beautiful, while a diamond with lower saturation might show a less intense and more washed-out blue.
Saturation in the Cape Series and Fancy Shaped Diamonds:

Both cape series diamonds (those with a yellow to brown colour range) and fancy shape diamonds (such as diamonds in the shape of emerald, oval, or pear) are graded on a scale of increasing saturation, in addition to other factors like hue and tone.
Cape Series Diamonds: These diamonds have a natural tint of yellow, brown, or orange and are graded for saturation on a scale that measures the intensity of these colours. The more vivid or intense the tint, the higher the saturation, and thus the greater the value.
Fancy Shape Diamonds: For fancy shape diamonds, saturation is also a critical element in grading. Fancy shape diamonds can come in a wide range of colours, and the saturation of these colours can affect the overall appeal of the diamond. A fancy shaped diamond with higher saturation will generally be more desirable, especially if the colour is highly vibrant and deep.
The Role of Saturation in Diamond Cutting:

While colour is often considered a matter of natural characteristics, the cutting of a diamond can also impact its perceived saturation. For example, a well-cut diamond may appear to have greater colour intensity and saturation as light is reflected and refracted more effectively within the diamond. Conversely, poor cutting can cause the diamond to lose some of its colour brilliance, making it appear less saturated.
Saturation and Fancy Coloured Diamonds:

Fancy coloured diamonds come in a wide variety of colours, including blue, green, pink, yellow, orange, red, and brown. The saturation level is particularly important when grading these diamonds. A fancy vivid pink diamond, for example, is one of the most sought-after diamonds due to its rich pink saturation, whereas a fancy light pink may not have the same level of appeal.
Factors Affecting Diamond Saturation:

Several factors can influence a diamond’s saturation, including its crystal structure, the presence of trace elements (such as boron for blue diamonds or nitrogen for yellow diamonds), and the way the diamond has been cut. The level of saturation can vary from diamond to diamond, even within the same colour family, and plays a crucial role in determining the rarity and value of the diamond.

Diamond saturation is a critical aspect of the diamond’s colour grading, determining the intensity and purity of its hue. The more intense and vivid the colour, the higher the saturation and, consequently, the value of the diamond. In fancy coloured diamonds, saturation is especially important, with diamonds in the fancy vivid and fancy intense categories being among the most highly sought after. Understanding the role of saturation allows diamond buyers to appreciate the depth and richness of coloured diamonds and choose the ones that best suit their personal preferences and value expectations.

July, 2017February, 2025

Red Diamond

A red diamond is an extremely rare and captivating coloured diamond with a natural red body colour. This distinctive hue is often considered the most rare of all diamond colours, with its unique shade being the result of an irregular crystal structure. Unlike other coloured diamonds, the red colour in red diamonds is not caused by the presence of impurities, but by specific structural defects within the crystal lattice, which affects how the diamond interacts with light.

Key Characteristics of Red Diamonds
Colour:

The red in red diamonds must be the predominant colour, and it may be modified by subtle undertones of pink or purple. These undertones add depth and complexity to the diamond’s overall appearance, creating a dynamic play of colour under different lighting conditions.
Red diamonds can range in tone from a light pinky-red to a deep, intense red, with the most prized examples exhibiting a vivid and saturated hue. The richness and intensity of the red are key factors in determining a red diamond’s rarity and value.
Colour Origin:

The distinct red colour of these diamonds is not due to traditional colouring agents like nitrogen or boron, which are often responsible for the hues of other coloured diamonds. Instead, the red colour arises from structural anomalies in the crystal lattice. These distortions cause light to bend in unique ways, giving the diamond its characteristic deep red shade.
The exact mechanism behind the creation of red diamonds is not entirely understood, which adds to their mystery and allure.
Rarity:

Natural red diamonds are the rarest of all coloured diamonds. They are so rare that they account for less than 0.1% of all natural diamonds. Their scarcity is due to the highly specific conditions required to form these diamonds. The majority of red diamonds come from a few select mines, particularly the Argyle Mine in Australia, which is one of the only sources of natural red diamonds.
As a result of their extreme rarity, red diamonds are often considered investment-grade stones, with prices escalating due to limited supply and growing demand.
Colour Grading:

The grading of red diamonds is somewhat different from other coloured diamonds. Red diamonds are typically graded on their colour saturation and intensity. Diamonds with a higher degree of vivid red colour and strong saturation are classified as fancy red diamonds, which are among the most valuable and sought-after types of coloured diamonds.
The Fancy Red classification is a coveted category, where the diamond displays a full, intense red hue with minimal interference from other colours.
Value and Investment
Investment Potential:
Due to their extreme rarity, high demand, and unique beauty, red diamonds are considered a valuable investment. As the supply of natural red diamonds continues to dwindle, especially with the closure of the Argyle Mine, prices are expected to rise steadily over time.
Red diamonds have become highly sought-after in the auction world, where they consistently fetch premium prices.

Pricing Factors:
The price of red diamonds is primarily determined by their colour quality, with the intensity and saturation of the red being the most important factors in determining value. Additionally, the size of the diamond also plays a role in its price, with larger red diamonds being exceptionally rare and significantly more expensive.

Red Diamond vs Other Coloured Diamonds
Diamond Colour Rarity Colour Tone Key Features
Red Extremely Rare Vivid Red, Deep Red Most rare, unique structural colour origin
Pink Rare Soft Pink to Vivid Pink Lighter hue, sometimes found with red undertones
Blue Rare Deep Blue to Light Blue Caused by boron, highly prized for its striking colour
Green Rare Light Green to Intense Green Natural radiation exposure causes the green hue
Yellow Common Light Yellow to Intense Yellow Caused by nitrogen, often brighter than other colours
Black Fairly Rare Deep, opaque black Intense colour, may have inclusions contributing to hue
Red Diamonds in Jewellery
Engagement Rings:

Red diamonds make a bold and captivating choice for engagement rings. Their rare and striking colour is perfect for individuals seeking something extraordinary and one-of-a-kind. When set in platinum or white gold, the red hue is often accentuated, creating a stunning contrast that is both elegant and memorable.
High-End Jewellery:

Due to their rarity and prestige, red diamonds are often featured in luxury jewellery collections and can be seen in high-end pieces, including necklaces, bracelets, earrings, and brooches. Their striking appearance and scarcity make them a statement piece in any collection.
Fancy Settings:

Red diamonds are typically set in settings that showcase their vivid colour, such as halo settings (where smaller diamonds surround the central red diamond) or three-stone designs that highlight the rarity and beauty of the diamond.

The red diamond is one of the rarest and most beautiful gemstones in the world, prized for its deep, captivating red hue and its unique structural formation. With limited availability and high demand, red diamonds are not only a luxurious addition to any jewellery collection but also an investment asset. Whether used in engagement rings, necklaces, or other fine jewellery, red diamonds are a symbol of both rarity and elegance, making them one of the most sought-after coloured diamonds in the world.

July, 2017February, 2025

Radiant Cut

The radiant cut is a diamond shape that combines the sparkle of a brilliant cut with the elegance of a square or rectangular shape. It is characterised by its distinct design, where the corners are cut off, creating a rounded appearance. This cut is crafted to maximise the brilliance (sparkle) and fire (colour dispersion) of the diamond, offering a unique and stylish look that is both modern and classic.

Key Features of the Radiant Cut
Shape:

The radiant cut can be either square or rectangular, but it features cut-off corners that distinguish it from other square or rectangular diamond cuts, such as the princess cut.
The shape provides a soft, rounded appearance while maintaining the bold geometric lines of a square or rectangle.
Facet Pattern:

Like the brilliant cut, the radiant cut typically features 58 facets. This facet arrangement helps the diamond reflect light efficiently, maximising its sparkle and brilliance.
Crisscrossing facets are arranged in a manner that enhances the diamond’s light return, creating a lively and vibrant look.
Cornered but Soft:

The cut corners of the radiant cut diamond reduce the sharpness seen in cuts like the princess cut. This helps prevent damage to the corners and makes the diamond more durable. The rounded edges give the diamond a softer look while still maintaining a square or rectangular silhouette.
Brilliance and Fire:

The radiant cut was specifically designed to maximise brilliance and fire, ensuring the diamond reflects light from all angles. This makes it particularly attractive for those seeking a diamond with high sparkle but a slightly different shape from the round brilliant cut.
Proportions and Symmetry in the Radiant Cut
Ideal Proportions: The ideal proportions for a radiant cut diamond depend on its shape. For a square radiant cut, an ideal length-to-width ratio is approximately 1:1, while for a rectangular radiant cut, the ideal ratio tends to fall between 1.25:1 and 1.5:1.
Symmetry: Like other cuts, symmetry plays an essential role in the beauty of a radiant cut diamond. Well-symmetrically cut radiant diamonds reflect light uniformly, creating a vibrant, well-balanced sparkle.
Advantages of the Radiant Cut
High Brilliance – Radiant cuts are designed for maximum sparkle, with 58 facets that reflect light from every angle, creating a lively and dazzling effect.

Versatile Appearance – The radiant cut combines the elegance of the princess cut and the round brilliant cut, making it a versatile choice for various jewellery styles, from engagement rings to earrings and necklaces.

Durability – The cut-off corners reduce the risk of chipping compared to the sharp corners of a princess cut, making radiant cuts a more practical option for everyday wear.

Unique Shape – The radiant cut offers a distinctive look that stands out from other popular cuts like round or princess cuts. Its ability to combine the best of both shapes makes it a preferred choice for those seeking something different.

Value for Money – The radiant cut typically retains more of the rough diamond compared to round brilliant diamonds, making it a cost-effective option for larger stones.

Setting Options for Radiant Cut Diamonds
Prong Setting:

A four-prong or eight-prong setting is commonly used to secure radiant cut diamonds, allowing maximum light exposure and highlighting the stone’s brilliance.
The prongs can be placed along the corners of the diamond to emphasise its shape.
Bezel Setting:

A bezel setting can encircle the edges of the diamond with metal, offering extra protection to the corners while providing a sleek, modern look.
Halo Setting:

A halo setting, where smaller diamonds encircle the centre radiant cut diamond, is a popular choice. It enhances the diamond’s size and sparkle while adding extra brilliance.
Tension Setting:

The tension setting is a bold, modern way to showcase a radiant cut diamond. The diamond appears to be floating between two metal bands, offering a minimalist yet striking design.
Radiant Cut vs. Other Cuts
Cut Type Shape Brilliance Best Feature
Radiant Cut Square/Rectangular Very High Unique blend of square/round elegance
Princess Cut Square Very High Sharp edges, square shape
Emerald Cut Rectangular Moderate Elegant, step-cut style
Round Brilliant Circular Very High Maximum brilliance and fire
Cushion Cut Square/Rounded Corners High Soft, vintage appearance

The radiant cut is a stunning and versatile diamond shape that balances brilliance and fire with the elegance of a square or rectangular shape. Its unique cut corners not only enhance its visual appeal but also improve the diamond’s durability. With high brilliance, a striking shape, and the ability to suit a variety of settings, the radiant cut is an excellent choice for those seeking a beautiful yet distinctive diamond that stands out in any piece of jewellery.

July, 2017February, 2025

Princess Cut

Diamond cut or shaped into a square or rectangle

The princess cut is a popular diamond shape known for its sharp, square or rectangular outline and exceptional brilliance. It is a modern, geometric cut that combines elements of both the brilliant cut and the step cut, offering a perfect balance of sparkle and elegance.

Characteristics of the Princess Cut
Shape – Square or slightly rectangular, with sharp, uncut corners.
Facet Pattern – A mix of brilliant and step-cut faceting, designed to maximize brilliance and fire.
Number of Facets – Typically ranges from 50 to 58 facets, depending on the specific design.
Cut Style – Modified brilliant cut with a pyramid-like structure when viewed from the side.
Brilliance and Fire
Despite its angular shape, the princess cut rivals the round brilliant cut in terms of sparkle. Its unique chevron faceting pattern helps to reflect and disperse light, creating excellent fire and brilliance.

Pros and Cons of the Princess Cut
Advantages:

High brilliance – Offers a stunning level of sparkle, second only to the round brilliant cut.
Modern and elegant look – The sharp, geometric style suits contemporary engagement ring designs.
More affordable per carat – Compared to round diamonds, princess cuts retain more rough diamond material, making them more cost-effective.
Considerations:

Sharp corners are vulnerable – Unlike round diamonds, princess cuts have pointed corners that can be prone to chipping if not properly protected by prongs.
Color and clarity are more visible – Due to its faceting style, lower clarity and color grades may be more noticeable, requiring careful selection.
Best Settings for Princess Cut Diamonds
Prong Setting – A four-prong or V-prong setting helps protect the delicate corners.
Bezel Setting – Offers maximum protection by encasing the edges in metal.
Halo Setting – Surrounds the princess cut with smaller diamonds, enhancing brilliance.
Channel Setting – Ideal for wedding bands or side stones, securing the diamond with a sleek, modern look.
Princess Cut vs. Other Cuts
Cut Style Shape Brilliance Best Feature
Princess Cut Square/Rectangular High Modern brilliance with sharp angles
Round Brilliant Circular Very High Maximum sparkle and fire
Emerald Cut Rectangular Moderate Elegant step-cut clarity
Cushion Cut Square/Rounded Corners High Soft, vintage appeal

The princess cut is a timeless and sophisticated diamond shape that offers exceptional brilliance in a modern, geometric form. Whether used in engagement rings or fine jewelry, it provides a bold yet elegant alternative to traditional round diamonds, combining beauty, affordability, and brilliance in one striking cut.

July, 2017February, 2025

Proportion Grade

proportions on a round brilliant cut diamond

The proportion grade is a qualitative assessment of the overall proportions of a round brilliant cut diamond. It evaluates how well the diamond’s dimensions, angles, and facet arrangements are balanced to maximize brilliance, fire, and scintillation.

Why Proportions Matter
The way a diamond is cut significantly impacts its light performance. If the proportions are too shallow or too deep, light may escape through the sides or bottom of the diamond rather than reflecting back to the viewer, reducing its brilliance. The ideal proportion grade ensures that the diamond reflects and refracts light efficiently, creating maximum sparkle.

How Proportion Grade is Determined
For round brilliant cut diamonds, proportion grading is based on several key measurements:

Table Percentage – The size of the top facet (table) relative to the total width of the diamond.
Depth Percentage – The total depth of the diamond (from table to culet) relative to its width.
Crown Angle – The angle between the table and the crown facets, affecting light dispersion (fire).
Pavilion Angle – The angle between the pavilion facets and the girdle, influencing light return.
Girdle Thickness – Affects durability and light performance.
Culet Size – Affects light leakage and appearance.
Proportion Grades in Round Brilliant Diamonds
Grading laboratories, such as the GIA (Gemological Institute of America), categorize proportion grades into different levels:

Excellent (EX) – Ideal proportions for optimal brilliance, fire, and scintillation. Light is perfectly reflected, creating a highly desirable sparkle.
Very Good (VG) – Slight variations in proportions that still allow excellent light performance, with minimal impact on brilliance.
Good (G) – Noticeable proportion variations that may result in light leakage, reducing the overall brightness.
Fair (F) – Unbalanced proportions causing significant light loss, making the diamond appear dull or lifeless.
Poor (P) – Severe proportion flaws leading to excessive light leakage, drastically affecting brilliance and beauty.
Proportion Grading for Fancy-Shaped Diamonds
Unlike round brilliant cut diamonds, fancy-shaped diamonds (e.g., princess, cushion, oval, emerald) do not receive a proportion grade. This is because there is no universal standard for the best proportions in fancy shapes—each shape has unique visual and performance characteristics that cannot be judged by a single set of criteria. Instead, fancy shapes are evaluated based on symmetry, polish, and overall cut quality.

Ideal Proportions for Round Brilliant Diamonds
While exact measurements may vary slightly, the following proportions are considered ideal for maximizing brilliance in a round brilliant cut diamond:

Table Size: 53%–58% of the diamond’s total width
Total Depth: 59%–63%
Crown Angle: 34°–35°
Pavilion Angle: 40.6°–41°
Girdle Thickness: Thin to Medium
Culet: None or Very Small

The proportion grade is a critical factor in determining a round brilliant cut diamond’s overall light performance and beauty. Diamonds with Excellent or Very Good proportion grades offer superior brilliance, making them highly desirable. While fancy-shaped diamonds are not proportion graded, their individual cut quality should still be carefully evaluated to ensure maximum visual appeal.

July, 2017February, 2025

Proportions

Relations between the dimensions and angles of a finished diamond.

In the context of diamond grading, proportions refer to the relationship between the dimensions and angles of a finished diamond. These elements play a crucial role in how well the diamond performs in terms of brilliance (brightness), fire (color dispersion), and scintillation (sparkle). The ideal proportions ensure that light enters the diamond, reflects off the internal facets, and exits in a way that maximizes the stone’s visual appeal.

Key Proportions in Diamond Grading
Several specific proportions are evaluated to determine how efficiently the diamond handles light and affects its overall appearance. These include:

Table Size

Definition: The table is the flat, top facet of the diamond. The table size is the percentage of the diamond’s overall width that the table occupies.
Importance: A table that is too large or too small can affect how light enters the diamond, potentially reducing the amount of sparkle and brilliance. The ideal table size helps balance light reflection and refraction for optimal sparkle.
Recommended Range: For a round brilliant cut, a table size of around 53%–58% is considered ideal.
Depth Percentage

Definition: The depth of a diamond is the measurement from the table to the culet (the tip at the bottom of the diamond). The depth percentage is calculated by dividing the diamond’s depth by its diameter and multiplying by 100.
Importance: The depth affects how well light travels through the diamond. A shallow depth can cause light to leak from the bottom, while a deep depth can prevent light from reflecting fully.
Recommended Range: The ideal depth percentage for a round brilliant cut diamond is generally 59%–63%.
Crown Angle

Definition: The crown angle is the angle between the diamond’s crown (the upper portion above the girdle) and the table.
Importance: The crown angle influences the diamond’s ability to reflect light and create fire (colorful flashes of light). If the angle is too steep or too shallow, light performance is diminished.
Recommended Range: An ideal crown angle for a round brilliant diamond is typically 34°–35°.
Pavilion Angle

Definition: The pavilion angle is the angle between the pavilion facets (the lower part of the diamond) and the girdle (the diamond’s outer edge).
Importance: The pavilion angle has a direct effect on light return. If the pavilion angle is too shallow or steep, light may escape through the bottom of the diamond, reducing sparkle.
Recommended Range: An ideal pavilion angle for a round brilliant diamond is typically around 40.6°–41°.
Girdle Thickness

Definition: The girdle is the widest part of a diamond, forming a boundary between the crown and pavilion. Girdle thickness refers to how thick or thin the girdle is.
Importance: The girdle’s thickness affects the durability and overall symmetry of the diamond. A girdle that is too thick can make the diamond appear smaller, while one that is too thin may make the diamond more susceptible to damage.
Recommended Range: A thin to medium girdle is often ideal for balance and durability.
Culet Size

Definition: The culet is the tiny facet at the bottom of the diamond, located at the tip of the pavilion. Culet size refers to the size of this facet.
Importance: A large culet can cause light leakage and affect the diamond’s appearance by making it look less bright and less crisp. A smaller or no culet is often preferred for optimal light performance.
Recommended Range: A no culet or very small culet is usually ideal.
Why Proportions Matter
The proportions of a diamond directly influence its light performance and visual appeal. When the proportions are balanced, light enters the diamond, bounces off its internal facets, and exits to create maximum sparkle and fire.

Maximized Brilliance – Proper proportions allow for better internal reflection, resulting in a more vibrant and brilliant diamond.
Enhanced Fire – Well-balanced proportions lead to more effective dispersion of light into the spectrum of colors, creating a diamond with bright flashes of color.
Improved Scintillation – Good proportions enhance the sparkle or scintillation, the flashes of light that occur as the diamond moves.
Proportions in Fancy-Shaped Diamonds
While proportions are crucial for round brilliant cut diamonds, fancy-shaped diamonds (e.g., princess, emerald, oval, pear) do not have standardized proportions. Instead, their light performance is assessed based on symmetry and cut quality. Each shape has unique visual characteristics that may require slightly different proportions to achieve optimal brilliance.

In diamond grading, proportions are fundamental to determining how well a diamond reflects and disperses light, which directly impacts its beauty, brilliance, and value. For round brilliant cut diamonds, adhering to the ideal proportions enhances the overall visual appeal and maximizes the stone’s sparkle. For fancy shapes, proportion grading is not standardized, but cut quality and symmetry still play a critical role in achieving a stunning diamond. Understanding these proportions is key when choosing the perfect diamond for any jewelry piece.

Relations between the dimensions and angles of a finished diamond. Examples of specific proportions are table size, depth percentage, and crown angle. Proportions are extremely important to the beauty, brilliance, and life in a diamond. Click here to learn more about proportions on a diamond grading report.