Diamonds – Page 62 – The Diamond Certification Laboratory of Australia (DCLA)

July, 2017February, 2025

Octahedron

An octahedron is one of the most sought-after crystal shapes for rough diamonds, featuring eight triangular faces arranged symmetrically. This shape resembles two four-sided pyramids joined at their base, forming a perfect geometric structure. Due to its natural symmetry and efficient cutting potential, octahedral rough diamonds are highly desirable for diamond cutting and manufacturing.

Characteristics of an Octahedral Diamond
Crystal Structure: Composed of eight equilateral triangular faces
Formation: Forms naturally under high pressure and heat within the Earth’s mantle
Symmetry: Well-balanced, making it one of the most efficiently cuttable rough diamond shapes
Occurrence: One of the most common and valuable rough diamond shapes found in nature
Why Octahedral Rough Diamonds Are Coveted
1. Ideal for Cutting Round Brilliant Diamonds
The octahedral shape is perfectly suited for cutting two round brilliant diamonds from a single rough stone, maximizing yield and minimizing waste.
Diamond cutters often cleave or saw the rough along its natural planes to create two symmetrical, high-quality diamonds.
2. Natural Growth of Diamonds
The octahedron reflects the cubic crystal system of diamonds, where atoms arrange themselves in the most stable geometric form.
Over millions to billions of years, carbon atoms bond in this shape under extreme pressure deep within the Earth.
3. High Clarity Potential
Since octahedral diamonds grow in a stable environment, they often develop with fewer inclusions compared to irregularly shaped rough stones.
Their internal structure is generally strong, reducing the risk of fractures during the cutting process.
Octahedral Diamonds in Cutting & Polishing
How Cutters Assess an Octahedral Rough Diamond:
Orientation: Experts determine the best way to cut the rough to achieve the highest carat yield.
Inclusion Mapping: If internal flaws are present, cutters adjust the cutting plan to eliminate or minimize them.
Cleaving/Sawing: The rough is often split along its natural grain to form two high-quality gemstones.
Common Diamond Cuts from an Octahedron:
Cut Style Why It’s Chosen for Octahedral Rough
Round Brilliant Uses the natural symmetry of the octahedron to produce two symmetrical stones
Princess Cut Retains a high percentage of the original rough weight
Cushion Cut Maximizes brilliance while preserving rough material
Octahedron vs. Other Rough Diamond Shapes
Rough Diamond Shape Description Cutting Potential
Octahedron Eight triangular faces, symmetrical High yield, excellent for round brilliants
Dodecahedron Twelve pentagonal faces, irregular More cutting challenges, lower yield
Macles (Twinned Crystals) Flattened, triangular shape due to twinning Often used for fancy cuts, less efficient for rounds
Cubo-octahedron Mix of cube and octahedron faces Good for step cuts like emerald or Asscher

The octahedron is the most desirable natural shape for rough diamonds due to its symmetry, high clarity potential, and efficient cutting yield. This structure allows diamond cutters to maximize the rough’s potential, often yielding two high-quality round brilliant diamonds from a single octahedral crystal. Its formation represents the natural stability of diamond growth, making it a prized find in the world of gemology.

July, 2017February, 2025

Off-Make

Trade term for a diamond that has been badly polished or finished.

The term “off-make” is a trade term used to describe a diamond that has been poorly cut, polished, or finished, resulting in flaws in its overall make. This means the diamond does not meet ideal proportions, symmetry, or polish standards, leading to reduced brilliance, fire, and overall aesthetic appeal.

Characteristics of an Off-Make Diamond
A diamond is considered off-make when it exhibits one or more of the following defects:

1. Poor Proportions
Too deep or too shallow – Affects light reflection and reduces brilliance.
Mismatched angles – Poor crown and pavilion angles lead to light leakage.
Uneven girdle thickness – Some areas may be too thick (wasting carat weight) or too thin (making the diamond vulnerable to chipping).
2. Weak Symmetry
Misaligned facets – When facets are uneven or not placed correctly, the diamond lacks balance.
Table and culet off-center – Affects the diamond’s optical performance and sparkle.
3. Low-Quality Polish
Visible polish lines or marks – Can create a dull appearance.
Rough or grainy surface texture – Reduces light reflection and brilliance.
4. Light Performance Issues
Nailhead effect – The center appears dark due to excessive depth.
Fish-eye effect – A distorted reflection of the girdle inside the table, caused by a shallow pavilion.
Windowing – When light passes straight through the diamond rather than reflecting back, making it appear see-through.
How Off-Make Affects a Diamond’s Value
1. Lower Market Demand
Off-make diamonds are considered less desirable by both jewelers and consumers because they lack brilliance and symmetry.

2. Reduced Sparkle & Fire
A well-cut diamond maximizes brilliance (white light reflection) and fire (color dispersion).
Off-make diamonds often appear lifeless, dull, or dark, even with good clarity and color.
3. Lower Resale & Appraisal Value
Since cut is the most important factor in a diamond’s beauty, a poorly made diamond will be valued lower than a well-cut stone of the same carat weight, clarity, and color.
4. Potential for Weight Retention Over Beauty
Some off-make diamonds are intentionally cut poorly to retain more carat weight from the rough, sacrificing quality for size.
How to Avoid Buying an Off-Make Diamond
1. Check the Cut Grade
Buy diamonds certified by DCLA, GIA, or AGS, which provide cut grades ranging from Excellent to Poor. Avoid stones with Fair or Poor cut grades.
2. Inspect Light Performance
Look at the diamond under different lighting conditions to check for dark areas, weak reflections, or excessive transparency.
3. Look for Proportion Guidelines
Ideal Table Size: 53-58% of the total width
Ideal Depth Percentage: 58-63%
Crown and Pavilion Angles: Well-balanced for optimal light return
4. Use a Loupe or Microscope
Check for symmetry, facet alignment, and polish marks.
5. Ask for an ASET or Ideal Scope Image
These tools reveal light leakage, helping determine if the diamond is well-cut.

July, 2017February, 2025

Natural Diamond

A natural diamond is a gemstone composed of crystallized carbon that was formed deep within the Earth’s mantle under extreme heat and pressure over 1 to 3 billion years ago. Unlike lab-grown diamonds, which are created in controlled environments, natural diamonds are mined from the Earth and are considered one of the rarest and most valuable gemstones.

Formation of Natural Diamonds
Natural diamonds form 100–200 km (62–124 miles) below the Earth’s surface, where intense pressure (725,000+ psi) and high temperatures (1,100–1,400°C) cause carbon atoms to bond in a unique cubic crystal structure. These diamonds are then transported to the surface through volcanic eruptions, specifically via kimberlite pipes—ancient volcanic conduits that carry rough diamonds upward.

Characteristics of Natural Diamonds
Composition:
Made of pure carbon arranged in a tetrahedral lattice, giving diamonds their exceptional hardness.
Hardness (Mohs Scale 10):
The hardest known natural material, making it highly resistant to scratches and wear.
Brilliance & Fire:
Due to its high refractive index (2.42), a well-cut diamond reflects and disperses light, creating its signature sparkle.
Unique Inclusions & Imperfections:
Most natural diamonds contain inclusions (internal characteristics) and blemishes (surface characteristics) that serve as fingerprints of their natural origin.
Rarity & Value:
Large, flawless natural diamonds are exceptionally rare, making them highly valuable compared to lab-grown alternatives.
Types of Natural Diamonds
1. White (Colorless) Diamonds
The most sought-after diamonds, graded on a color scale from D (colorless) to Z (light yellow or brown).
The less color, the higher the value.
2. Fancy Color Diamonds
Natural diamonds can exhibit blue, pink, yellow, green, orange, and even red hues due to trace elements or structural irregularities.
Examples:
Blue diamonds (trace boron) – Example: The Hope Diamond
Pink diamonds (structural distortions) – Example: Argyle Pink Diamonds
Yellow diamonds (trace nitrogen) – Example: Tiffany Yellow Diamond
3. Industrial Diamonds
Low-quality natural diamonds used in cutting, drilling, grinding, and polishing tools due to their extreme hardness.
How Natural Diamonds Are Mined
Natural diamonds are extracted from the Earth using various mining techniques:

Kimberlite Pipe Mining (Primary Source)

Diamonds are found in kimberlite pipes, ancient volcanic conduits rich in diamond-bearing rock.
Mined using open-pit or underground methods.
Alluvial Mining (Secondary Source)

Diamonds eroded from kimberlite pipes are transported by rivers and accumulate in riverbeds or coastal areas.
Marine Mining

Specialized ships mine diamonds from the ocean floor, particularly off the coast of Namibia and South Africa.
How Natural Diamonds Are Identified
To distinguish a natural diamond from a lab-grown or synthetic diamond, experts use advanced testing and certification from recognized gemological labs like DCLA, GIA, and AGS.

Key Identification Methods:
Inclusions & Growth Patterns: Natural diamonds contain unique inclusions, such as tiny crystals, feathers, or graining patterns, absent in lab-grown diamonds.
Fluorescence & Phosphorescence: Some natural diamonds exhibit fluorescence under UV light, while lab-grown diamonds may show different reactions.
Spectroscopy & Advanced Testing: High-tech tools like FTIR (Fourier-transform infrared spectroscopy) and UV-Vis spectrometry help differentiate natural diamonds from synthetic or treated ones.
Natural Diamonds vs. Lab-Grown Diamonds
Feature Natural Diamond Lab-Grown Diamond
Formation Formed over billions of years in Earth’s mantle Created in weeks using HPHT or CVD methods
Origin Mined from the Earth Manufactured in a lab
Inclusions Natural growth patterns and inclusions Different internal characteristics, sometimes with metallic inclusions (HPHT)
Rarity Extremely rare, especially high-quality stones Mass-produced
Price Higher due to rarity Generally 50–70% cheaper
Resale Value Strong resale and investment value Limited resale market
Ethical Concerns Some concerns over ethical sourcing (unless from certified conflict-free sources) Considered conflict-free and more sustainable
Ethical & Sustainable Sourcing of Natural Diamonds
Concerns over “blood diamonds” (conflict diamonds) led to the Kimberley Process Certification Scheme (KPCS), which ensures that natural diamonds are ethically sourced and do not fund conflicts.

Reputable diamond companies, including DCLA-certified brands, focus on:

Conflict-free mining practices
Fair labor policies
Sustainable environmental impact reduction
Why Choose a Natural Diamond?
Timeless Value: Unlike lab-grown diamonds, natural diamonds retain strong resale and investment value.
Unique & One-of-a-Kind: Each natural diamond has its own history, inclusions, and growth patterns, making it a unique creation of nature.
Symbolism & Tradition: Used in engagement rings, heirlooms, and high jewelry, natural diamonds carry deep emotional and historical significance.

July, 2017February, 2025

Needle

A needle inclusion is a type of internal characteristic found in natural diamonds. It appears as a long, thin, needle-like crystal trapped inside the diamond during its formation. These inclusions are often transparent or white, but they can also appear in shades of black, brown, or other colors, depending on the type of mineral present.

How Needle Inclusions Form
Natural diamonds form over billions of years deep within the Earth’s mantle under extreme pressure and heat. During this process, various mineral deposits, gases, or even other diamond crystals can become trapped inside the growing diamond. When these inclusions form in an elongated shape, they are classified as needle inclusions.

Composition: Needle inclusions can be made of other minerals (such as garnet, olivine, or pyroxene) or even diamond itself.
Growth Influence: The presence of a needle inclusion can sometimes indicate the diamond’s growth pattern and conditions within the Earth.
Appearance of Needle Inclusions
Shape: Thin, elongated, needle-like structure
Color: Usually transparent or white, but can also be black, brown, or yellow depending on the trapped material
Size: Ranges from microscopic (only visible under magnification) to larger inclusions that may affect transparency
Position: Found anywhere in the diamond, including near the surface, within the pavilion, or in the crown
Impact of Needle Inclusions on Diamond Quality
1. Clarity Grade
Needle inclusions affect a diamond’s clarity grade, which is assessed by laboratories like DCLA, GIA, and AGS.

If the needle is small and not visible to the naked eye, it may have minimal impact on the clarity grade.
If the needle is large, numerous, or positioned in a way that affects transparency, it may lower the diamond’s clarity rating significantly.
2. Visibility in Jewelry
Small needles in the pavilion (bottom of the diamond): Often not noticeable and have little impact on beauty.
Larger needles near the table (top flat facet): May be more visible and slightly reduce brilliance.
Clusters of needle inclusions: When multiple needles form in the same area, they can create a hazy or cloudy effect, reducing the diamond’s overall brightness.
3. Structural Integrity
Unlike surface-reaching inclusions (such as feathers or cavities), needle inclusions do not typically weaken a diamond’s durability.
However, if located near the girdle or in a region of high stress, a large needle inclusion might slightly affect the diamond’s strength.
How to Identify Needle Inclusions
1. Under Magnification
Needles are difficult to spot with the naked eye but can be seen under a 10x jeweler’s loupe or a microscope. They often appear as thin, hair-like lines inside the diamond.

2. Diamond Grading Reports
Professional reports from DCLA, GIA, or AGS will note needle inclusions under clarity characteristics.
Needles are often indicated on a diamond’s plot diagram, showing their location and size.
3. Using Fluorescence & Light Scattering
Some needles become more visible under UV light.
Strong lighting may make them appear as tiny bright or dark streaks inside the diamond.
Needle Inclusions vs. Other Inclusions
Inclusion Type Description Impact on Clarity
Needle Thin, elongated crystal trapped inside the diamond Minimal unless large or clustered
Pinpoint Tiny, dot-like crystal Very minor effect
Cloud Group of tiny pinpoints, creating a hazy look Can lower brilliance if dense
Feather Small crack or fracture May impact durability
Crystal Distinct mineral inclusion, often shaped like a small crystal Can be noticeable if dark
Are Needle Inclusions a Dealbreaker?
Not necessarily.

If small and not visible to the naked eye, needle inclusions have little impact on beauty or value.
If multiple needles cluster together, they might create a cloudy effect, reducing transparency and brilliance.
Always review a diamond’s clarity in person or with a magnification tool to determine if the needle inclusion affects its overall appearance.

July, 2017February, 2025

Natural

A natural refers to a portion of the original rough diamond’s outer surface that remains unpolished on a finished, faceted diamond. This feature is intentionally left on the stone during the cutting and polishing process and is typically found along the girdle—the outer edge of the diamond that separates the crown (top) from the pavilion (bottom).

Why Are Naturals Left on a Diamond?
Maximizing Carat Weight

Diamond cutters aim to retain as much of the rough stone as possible. Removing all natural surfaces may require excessive cutting, reducing the final carat weight of the polished diamond.
Preserving Crystal Integrity

Some rough diamonds have growth lines or inclusions that, if cut away, could weaken the stone or impact its durability. Leaving a natural in a strategic area helps maintain the diamond’s overall strength.
Minimizing Waste

Since natural diamonds are rare and valuable, preserving part of the rough minimizes unnecessary loss of material during cutting.
Proof of Natural Origin

In some cases, gemologists and collectors appreciate naturals as evidence that the diamond was cut from a genuine rough stone rather than being lab-grown or heavily altered.
Impact on a Diamond’s Appearance and Quality
Polish Grade:

Naturals are considered minor surface features and are factored into the polish grade of a diamond. A diamond with significant naturals may receive a lower polish grade from gemological laboratories like DCLA, GIA, or AGS.
Location Matters:

If confined to the girdle area, naturals do not significantly affect the diamond’s overall appearance, brilliance, or value.
If present on the crown or table (top facets), they may be more visible and could impact the diamond’s aesthetic appeal.
Girdle Thickness Considerations:

Some naturals can contribute to an uneven girdle thickness, which might affect durability. A very thin girdle with a natural could increase the risk of chipping.
How to Identify a Natural in a Diamond?
Visible under Magnification
Naturals are typically small, textured, and may appear frosty or grainy under a jeweler’s loupe (10x magnification) or a microscope.
GIA & DCLA Reports
If a diamond has a natural, it is often noted in the grading report, usually under the clarity characteristics or polish comments section.
Naturals vs. Other Surface Features
Natural vs. Extra Facet:
A natural is an original rough diamond surface left untouched, while an extra facet is a man-made additional cut that is not part of the standard faceting pattern.
Natural vs. Cavity:
A natural is a minor surface remnant, whereas a cavity is an indentation or deeper surface flaw that can affect durability.
Are Naturals a Flaw?
Not necessarily. If located on the girdle, naturals are generally not a concern for beauty or durability. They do not impact the diamond’s brilliance or fire, and they are considered an acceptable feature in diamond cutting, especially for maximizing weight retention.

However, if a natural extends beyond the girdle onto visible facets, it could slightly affect the stone’s appearance and might be more noticeable.

July, 2017February, 2025

Milky Diamond

A milky diamond refers to a gemstone that exhibits a cloudy or hazy appearance, which results in reduced transparency, brilliance, and overall life of the stone. This milky effect can significantly affect the diamond’s visual appeal, as it diminishes the stone’s ability to reflect light and sparkle. The term “milky” is used to describe diamonds that appear opaque or have a frosted, white haze that can obscure the clarity and sparkle of the diamond.

There are several factors that can contribute to a diamond being described as milky:

Cloudy Inclusions: The most common cause of a milky appearance is the presence of dense, white, or opaque inclusions inside the diamond, known as “clouds.” These inclusions scatter light within the stone, making it appear hazy and reducing its brilliance. Clouds are generally made up of tiny crystals of minerals or gas bubbles trapped inside the diamond during its formation. While small clouds may have little effect on the diamond’s appearance, dense or large clouds can result in a noticeable milky effect.

Strong Fluorescence: Another factor that can cause a diamond to appear milky is intense fluorescence. Fluorescence refers to the emission of a visible light when the diamond is exposed to ultraviolet (UV) light. Diamonds that exhibit strong fluorescence, particularly blue fluorescence, may appear milky or hazy under certain lighting conditions, especially in daylight or under UV light. In some cases, strong fluorescence can create a visible bluish cloudiness in the diamond’s appearance, leading to a milky look.

Grading of Transparency: The DCLA (Diamond Certification Laboratory of Australia) uses a specific grading system to evaluate diamonds based on factors such as clarity, cut, colour, and transparency. When it comes to transparency, the DCLA assesses the diamond’s ability to transmit light and its overall visual quality. A milky diamond will generally receive a lower transparency grade due to the diminished light return caused by internal inclusions, fluorescence, or other optical issues. A diamond with a reduced transparency grade will appear less vibrant and lifeless compared to a perfectly clear stone.

Other Factors: In addition to inclusions and fluorescence, the clarity and overall quality of the diamond’s cut can also influence the diamond’s transparency. A poorly cut diamond, or one with irregularities in the facets, can exacerbate the milky effect by causing light to be scattered in a way that reduces its brilliance.

Impact on Value:
Milky diamonds tend to have a lower value compared to clear diamonds because their reduced transparency results in a diminished visual appeal. The milky effect makes them less desirable for high-end jewelry, where brilliance and clarity are highly valued. However, depending on the severity of the milky appearance, some buyers may still find these diamonds attractive for specific designs or purposes, such as lower-cost pieces or designs that mask the effect with intricate settings.

DCLA Transparency Grade:
When diamonds are certified by the DCLA, one of the factors considered is the diamond’s transparency. The transparency grade of a diamond can be influenced by a variety of internal and external factors. A milky diamond, due to its hazy or cloudy appearance, would likely receive a lower transparency grade, indicating that it does not possess the ideal light return and brilliance expected from a high-quality diamond. The DCLA’s grading system provides an objective way to assess these characteristics, allowing buyers and sellers to make informed decisions about the diamond’s quality and value.

July, 2017February, 2025

Mohs Scale

The Mohs Scale of Hardness is a qualitative scale that ranks minerals based on their ability to resist scratching. Developed by German mineralogist Friedrich Mohs in 1812, the scale is widely used in geology, gemology, and material science to compare the hardness of different minerals and gemstones. It ranges from 1 (softest) to 10 (hardest), with each mineral capable of scratching those ranked below it while being scratched by those ranked above it.

Mohs Scale of Hardness – Ranking of Minerals
Mohs Hardness Mineral Common Comparison
1 Talc Very soft; can be scratched by a fingernail; found in talcum powder.
2 Gypsum Soft; can be scratched by a fingernail; used in plaster and drywall.
3 Calcite Can be scratched by a copper coin; found in limestone and chalk.
4 Fluorite Can be scratched by a knife blade; used in fluorine production.
5 Apatite Can be scratched by a steel nail; found in teeth and bones.
6 Orthoclase Feldspar Harder than glass; a common mineral in granite.
7 Quartz Can scratch glass and steel; commonly found in sand and gemstones like amethyst and citrine.
8 Topaz A durable gemstone; harder than quartz and feldspar.
9 Corundum Includes sapphires and rubies; extremely hard, only scratched by diamond.
10 Diamond The hardest naturally occurring substance; used in cutting tools and jewelry.
Understanding the Mohs Scale
The Mohs scale is ordinal, meaning the difference in hardness between minerals is not proportional. For example, diamond (10) is about four times harder than corundum (9), even though the scale suggests a difference of only one unit.
Some synthetic materials and alloys can exceed the hardness of natural minerals. For example, tungsten carbide and cubic boron nitride have hardness levels approaching that of diamond.
While hardness measures scratch resistance, it does not indicate a mineral’s toughness or resistance to breaking. Diamond, while the hardest mineral, is brittle and can be shattered by a sharp blow.
Mohs Scale and Gemology
In gemology, the Mohs scale helps determine the durability of gemstones for everyday wear. Harder stones (e.g., diamond, sapphire, ruby) are ideal for engagement rings and jewelry exposed to frequent wear, while softer stones (e.g., opal, pearl, turquoise) require extra care to avoid scratches.

July, 2017February, 2025

Melee

Melee diamonds are small, polished diamonds that typically weigh less than 15 points (0.15 carats) each. These diamonds are often used in settings where multiple stones are grouped together to create a brilliant and dense appearance of sparkle, especially in intricate jewelry designs such as pavé, halo, and channel settings.

The word “melee” comes from the French term mêlée, which means “a conflict” or “a jumble.” In the context of diamonds, it refers to the arrangement of small stones, often set in close proximity, to achieve a cohesive and eye-catching visual effect.

Despite their smaller size, melee diamonds can still offer high clarity and quality, depending on the individual stone’s cut, colour, and clarity. They are typically graded collectively, meaning that instead of each stone being individually assessed for its qualities, the melee as a whole is evaluated for its overall consistency and aesthetic appeal. This makes melee diamonds more affordable compared to larger stones, while still offering considerable brilliance and impact when used in larger jewelry designs.

Melee diamonds are especially popular in engagement rings, wedding bands, and earrings, where they complement a larger center diamond or gemstone. Due to their smaller size, they are generally used to accentuate the design, offering added sparkle without taking attention away from the central feature of the piece. Moreover, the intricate settings often used to hold melee diamonds can increase the overall value of a piece by adding complexity and refinement to its craftsmanship.

Because of their relatively small size, melee diamonds are often sold in bulk or pre-set into jewelry, and they are sometimes categorized by weight groups, such as “single cut” or “full cut” melee diamonds, each with its own level of precision in cutting. They are frequently sourced from diamond wholesalers or dealers who specialize in smaller stones, and they can be a cost-effective option for those looking to add diamond accents to their jewelry collections.

Individual melee diamonds may not carry the same weight or monetary value as larger stones, their combined effect can create stunning jewelry pieces that are both beautiful and economically accessible.

July, 2017February, 2025

Marquise Cut

The marquise cut is a diamond shape that is elongated and features two pointed ends, creating an elegant, oval-like shape. This cut is named after the Marquise de Pompadour, the mistress of King Louis XV of France, who is said to have commissioned a diamond in this shape to resemble the smile of the Marquise. The shape is often associated with royalty and sophistication, as it combines beauty with a sense of regal charm.

Also known as a navette (which is the French term for “little boat”), the marquise cut’s design is reminiscent of a boat’s hull, with its long, sweeping lines and pointed ends. This cut is distinctive and versatile, often used in rings, earrings, and necklaces to create a striking and elongated visual effect.

Characteristics of a Marquise Cut
Shape and Proportions:

The marquise cut is an elongated oval with pointed tips at both ends, giving it a symmetrical and graceful appearance. The length-to-width ratio can vary, but it is typically quite long and narrow, which enhances the illusion of a larger size.
The length of the diamond can range from about 1.5 to 2.5 times its width, and the exact ratio depends on the preference of the buyer or the designer. A diamond with a more elongated shape will often appear larger than a round diamond of the same carat weight.
Brilliance and Sparkle:

The marquise cut is designed to maximise the diamond’s brilliance, meaning it reflects a high degree of light, resulting in an eye-catching, sparkly appearance. This is due to the number of facets that are carefully aligned to reflect light in the optimal manner.
The elongated shape enhances the visual size of the diamond, making it look larger than a round brilliant cut of the same weight. It also offers the added benefit of a larger surface area to show off the diamond’s brilliance.
Facets and Cut:

The marquise cut is usually faceted similarly to a round brilliant diamond, with 58 facets that maximise light reflection. The crown of the diamond, or the top part, has a series of triangular and kite-shaped facets, which work together to create the sparkle.
Due to the pointed ends, it is important for the cutter to ensure that these areas are not too sharp, as they can make the diamond more susceptible to damage. The cutting process focuses on maintaining the integrity of the shape and ensuring that the facets are aligned to produce the maximum brilliance and fire.
Unique Design and Versatility:

The marquise cut’s distinctive elongated form makes it a popular choice for engagement rings, especially when the goal is to make the diamond appear larger. Its shape is particularly flattering for smaller fingers, as it creates the illusion of length and elegance.
The marquise cut is also versatile in its use in jewellery design, as it pairs well with both traditional and modern settings. It can be used in rings, pendants, earrings, and bracelets, and it is often surrounded by other diamonds or gemstones to enhance its overall appearance.
Visual Appeal:

The elongated silhouette of a marquise cut diamond offers a slimming effect on the finger or the wearer’s appearance, making it a popular choice for those who want to emphasise elegance and sophistication. The cut also provides optical illusions, making the stone appear larger and more slender.
The pointed ends, in particular, create a dramatic and bold look, making marquise diamonds stand out in jewellery pieces. This cut is often chosen by those who want a distinctive, eye-catching piece that is unique and memorable.
Considerations When Choosing a Marquise Cut
Proportions and Symmetry:

When selecting a marquise cut diamond, the proportions and symmetry of the shape are essential. An asymmetrical or improperly proportioned marquise cut can result in a less desirable appearance. For example, a diamond that is too elongated or too broad might not offer the same balance and beauty as one with ideal proportions.
Symmetry is particularly important with the marquise cut, as uneven points or misaligned facets can detract from the overall sparkle and visual appeal.
Length-to-Width Ratio:

As mentioned, the length-to-width ratio is a key consideration for a marquise cut diamond. A ratio that is too extreme (e.g., overly long and narrow) may appear out of proportion, while a more balanced ratio (typically around 1.5 to 2.0) will provide a more harmonious and aesthetically pleasing appearance.
Pointed Ends:

The pointed ends of the marquise cut are vulnerable to damage, such as chipping, if the diamond is not set properly or if it is subjected to physical stress. For this reason, many buyers opt for a protective setting that shields the points. A bezel setting or a setting with raised prongs can help protect these vulnerable areas.
Clarity Considerations:

The clarity of a marquise cut diamond is particularly important because inclusions that appear near the pointed ends can be more noticeable due to the way light interacts with the shape. When purchasing a marquise cut diamond, it’s wise to choose one with minimal inclusions near the tips, as these can be more visible and detract from the diamond’s brilliance.
Popularity and History of the Marquise Cut
The marquise cut has remained a popular choice for engagement rings and jewellery designs for centuries. Its timeless appeal is linked to its association with royalty, particularly after it was named after the French Marquise de Pompadour. The shape has been embraced in various forms of luxury jewellery, and its sleek, sophisticated design continues to attract those seeking a distinctive, elegant piece.

The marquise cut is also a symbol of individuality, offering a unique alternative to traditional round brilliant or cushion-cut diamonds. It provides an option for those who want a ring or piece of jewellery that stands out, while still showcasing the brilliant qualities of the diamond.

July, 2017February, 2025

Lower-Girdle Facets

The lower-girdle facets are crucial elements in the overall symmetry and brilliance of a diamond. These triangle-shaped facets are located on the pavilion of the diamond, directly adjacent to the girdle, which is the outer edge of the diamond. The pavilion refers to the bottom part of the diamond, below the girdle, which is responsible for reflecting light back through the crown and into the observer’s eye.

Position and Structure
Location: The lower-girdle facets are positioned on the pavilion of the diamond, near the girdle. They are situated just below the main facets of the pavilion, including the main pavilion facets, which are the large, flat surfaces that reflect light into the crown.

Shape: These facets are typically triangle-shaped, although their size and exact proportions can vary depending on the cut of the diamond. In some diamonds, these lower-girdle facets may be slightly elongated or modified, but they usually maintain a triangular form.

Function: The primary function of the lower-girdle facets is to help direct light in the diamond, contributing to its brilliance and scintillation. These facets work by reflecting light that enters the pavilion from below, which then bounces back through the crown of the diamond, creating the visual effects that make diamonds sparkle. The interaction between the light and these facets is essential in maximizing the diamond’s overall visual appeal.

Impact on Diamond Performance
Brilliance:

The brilliance of a diamond is its ability to reflect white light. The lower-girdle facets play an important role in this by directing light from the pavilion back into the crown. When the light is properly reflected, it bounces back to the viewer’s eye, enhancing the diamond’s brightness.
Scintillation:

Scintillation refers to the flashes of light that occur when a diamond moves or is viewed from different angles. The lower-girdle facets help enhance scintillation by creating additional reflections and refractions of light. Their triangular shape and position allow them to catch light from various angles, contributing to the diamond’s overall sparkle.
Symmetry:

Properly aligned and symmetrical lower-girdle facets are essential to the overall symmetry of the diamond. When the facets are evenly proportioned, the diamond will have a more visually appealing appearance, with well-defined light reflections and a balanced sparkle. Any irregularities in the alignment or shape of these facets can lead to an uneven distribution of light, reducing the diamond’s brilliance.
Grading the Lower-Girdle Facets
In diamond grading, the quality of the lower-girdle facets is considered as part of the overall cut grade, which evaluates how well the diamond has been shaped and proportioned to maximize its brilliance, fire, and scintillation. Some of the factors that affect the grading of the lower-girdle facets include:

Size and Proportion:

The size and proportion of the lower-girdle facets should be well balanced with the other facets of the diamond, including the main pavilion facets and the upper girdle facets. Proper proportions contribute to the diamond’s overall symmetry and visual appeal.
Symmetry:

Symmetry is one of the key components of diamond grading. Lower-girdle facets should be symmetrical, with uniform size and placement. Any misalignment or uneven facet sizes can disrupt the flow of light through the diamond and impact its overall performance.
Polish:

A well-polished surface on the lower-girdle facets enhances the diamond’s ability to reflect light. Poor polishing can lead to a dull appearance and reduce the brilliance of the diamond.
Role in Different Diamond Cuts
While lower-girdle facets are typically found in round brilliant cut diamonds, their placement and function can also be seen in other shapes that share similar cutting structures. However, the round brilliant cut diamond relies most heavily on the lower-girdle facets to achieve optimal light performance.

Round Brilliant Cut:

In the round brilliant cut, the lower-girdle facets are particularly important in creating the characteristic sparkle and fire that this cut is known for. The precise arrangement of these facets ensures that the diamond exhibits maximum brilliance and scintillation.
Other Fancy Cuts:

While fancy shapes like emerald, princess, or asscher cuts have different facet structures, they still rely on the principles of light reflection and refraction that are found in the lower-girdle facets of the round brilliant cut. For these shapes, the positioning and number of lower-girdle facets can vary, but their purpose remains the same: to enhance the diamond’s brilliance.
Impact of the Lower-Girdle Facets on Diamond Value
Diamonds with well-proportioned and well-cut lower-girdle facets typically have better light performance, meaning they will display more brilliance, scintillation, and fire. As such, diamonds with ideal or well-graded lower-girdle facets are generally considered more valuable because they are more visually appealing. Poorly proportioned or poorly cut lower-girdle facets can negatively affect the diamond’s performance, reducing its overall desirability and value.