Category: Glossary

Eye-Clean Diamond: Understanding Clarity
An eye-clean diamond refers to a diamond that has no visible inclusions or blemishes when viewed with the naked eye from a standard viewing distance (about 15–30 cm). This term is important in diamond clarity grading, as it helps buyers choose diamonds that appear flawless without the high cost of an internally flawless (IF) or very high-clarity grade stone.

Key Factors in Eye-Clean Diamonds
Diamond Clarity Grades & Eye-Clean Standards

FL (Flawless) & IF (Internally Flawless) – Always eye-clean (no inclusions even under magnification).
VVS1 & VVS2 (Very, Very Slightly Included) – Essentially eye-clean, with inclusions only visible under 10x magnification.
VS1 & VS2 (Very Slightly Included) – Generally eye-clean, with VS2 possibly showing inclusions in larger stones (2.00+ carats).
SI1 (Slightly Included 1) – May be eye-clean, but some stones might have visible inclusions. Careful selection is needed.
SI2 & I1 (Included 1) – Typically not eye-clean; inclusions are often visible without magnification.
I2 & I3 (Heavily Included) – Clearly visible inclusions that affect beauty and durability.
Size & Location of Inclusions

Inclusions near the edges (girdle) are less noticeable than those under the table (center of the diamond).
White or faint inclusions (like feathers or clouds) blend better than dark or black inclusions.
Smaller diamonds (under 1.00 ct) tend to be more eye-clean at lower clarity grades than larger diamonds.
Diamond Cut & Brilliance

Brilliant cuts (Round, Cushion, Princess, Radiant) can mask inclusions due to their sparkle.
Step cuts (Emerald, Asscher) reveal inclusions more easily because of their open faceting style.

Extra Facet in a Diamond
An extra facet in a diamond is an additional facet that is not part of the standard faceting pattern. These extra facets are typically unintended and can affect the diamond’s symmetry and overall appearance.

Causes of Extra Facets
Polishing Adjustments: Sometimes, extra facets are added during polishing to remove inclusions or surface blemishes.
Damage Repair: If a diamond has a small chip, an extra facet may be placed to smooth out the flaw.
Cutting Errors: Occurs when a cutter mistakenly places an additional facet that is not required by the ideal facet arrangement.
Intentional Artistic Choice: In rare cases, an extra facet may be added to enhance the diamond’s light performance.
Impact on Diamond Quality
Symmetry Grade Reduction – Extra facets can lower a diamond’s symmetry grade, affecting its overall cut rating.
Less Noticeable on the Pavilion – If the extra facet is placed on the pavilion (bottom part), it may not impact the diamond’s face-up appearance.
More Visible on the Crown or Table – If the extra facet is near the table (top surface), it can affect light reflection and reduce brilliance.

Effect on Value – While minor extra facets may have little effect on price, larger or poorly placed ones can decrease a diamond’s value.

How to Identify an Extra Facet?
Found in a diamond grading report, usually noted under clarity characteristics.
Labeled as “Extra Facet” on certification reports from GIA, DCLA, IGI, HRD, etc.
Visible under 10x magnification or a jeweller’s loupe.
Should You Buy a Diamond with an Extra Facet?
If it’s on the pavilion and doesn’t affect brilliance, it’s usually acceptable.
If it’s on the crown or table, consider how much it affects symmetry and light performance.
Always check the diamond certification report and inspect the diamond in different lighting conditions before purchasing.

An extra facet is an additional, unplanned facet on a diamond that is not part of the standard faceting pattern. It is usually added to remove a small inclusion, blemish, or natural rough spot without significantly altering the diamond’s symmetry.

Diamond Equivalent Colour Grade (ECG)
The Diamond Equivalent Colour Grade (ECG) is a system used to compare the colour grades of diamonds assessed by different grading laboratories. It provides a reference for understanding how diamonds graded by one lab compare to those graded by another, ensuring consistency in colour evaluation.

Why is ECG Important?
Different diamond grading labs may have slight variations in colour grading.
ECG helps align grading standards, making it easier for buyers, jewelers, and investors to compare diamonds accurately.

It is particularly useful when dealing with non-GIA or non-DCLA graded diamonds.
Comparison of Diamond Colour Grades Across Laboratories

GIA Grade DCLA (CIBJO Standard) HRD Grade IGI Grade AGS Grade EGL Grade
D (Colourless) D D D 0 000
E (Colourless) E E E 0.5 000
F (Colourless) F F F 1 000
G (Near Colourless) G G G 1.5 000
H (Near Colourless) H H H 2 000
I (Near Colourless) I I I 2.5 00
J (Near Colourless) J J J 3 00
K (Faint Yellow) K K K 3.5 00
L (Faint Yellow) L L L 4 0
M (Faint Yellow) M M M 4.5 0
N-R (Very Light Yellow) N-R N-R N-R 5-7 0
S-Z (Light Yellow) S-Z S-Z S-Z 7.5-10 0

GIA (Gemological Institute of America) is considered the strictest in grading.
DCLA (Diamond Certification Laboratory of Australia) follows CIBJO standards, aligning closely with GIA.
IGI, HRD, and EGL may have slightly looser grading standards.
AGS (American Gem Society) uses a 0-10 numerical scale where 0 = D (colourless) and 10 = Z (light yellow).

Emerald Cut Diamond: A Timeless Classic
The Emerald Cut Diamond is a step-cut diamond known for its elegant, elongated shape and hall-of-mirrors effect. It is one of the most sophisticated diamond cuts, often chosen for engagement rings and fine jewelry due to its vintage charm and unique sparkle.

Key Characteristics of an Emerald Cut Diamond
1. Shape & Faceting Style
Rectangular shape with cut corners
Step-cut faceting: Unlike the brilliant-cut diamonds that maximize sparkle, the Emerald Cut has long, parallel step-like facets (usually 57 or 58 facets).
Large, open table: The wide top surface enhances clarity, making inclusions more visible compared to round or cushion cuts.
Hall of Mirrors Effect: The parallel step-cut facets create a mesmerizing play of light and dark reflections.
2. Facet Structure
Crown (Top): Large, flat table with linear step facets.
Girdle (Middle): The widest part, providing durability.
Pavilion (Bottom): Parallel step facets that create depth and reflection.
Cut Corners: Prevent chipping and add to durability.
Emerald Cut Diamond Proportions & Ratio
Ideal Length-to-Width Ratio:

1.30 to 1.50 is the most common and elegant proportion.
Squarer Emerald Cuts (1.20-1.30) are sometimes called “Asscher Cuts” (which are more octagonal).
Depth Percentage:

Ideally between 60% and 70% to balance light reflection.
Table Percentage:

Typically 60% to 68% of the total width.
Brilliance & Sparkle
Subtle, understated sparkle: Unlike a Round Brilliant Cut, which maximizes fire and brilliance, the Emerald Cut has a softer glow, focusing more on clarity and elegance.
Less dispersion (fire): The step-cutting style does not break light into as many colorful flashes as a brilliant cut.
More clarity-dependent: Due to the large open facets, inclusions and flaws are more visible.

Diamond durability refers to a diamond’s ability to withstand wear, scratching, chipping, and breaking over time. As the hardest naturally occurring substance on Earth, diamonds are renowned for their exceptional hardness, but their overall durability depends on several other factors as well. These factors include their toughness (resistance to breaking or fracturing), clarity (internal inclusions or flaws), and how they are handled or set in jewelry.

Key Factors Affecting Diamond Durability:
Hardness:

Hardness is the measure of a material’s resistance to scratching. On the Mohs scale of hardness, diamonds score a 10, the highest possible rating, which means they can only be scratched by other diamonds.
This makes diamonds extremely resilient to surface damage from everyday wear, such as scratches from other materials like metals or other gemstones.
Toughness:

Toughness refers to a material’s ability to resist fracturing or chipping when subjected to impacts. While diamonds are incredibly hard, they are not necessarily tough.
Diamonds have what is called cleavage, which means they have planes of weakness within their crystal structure. If struck with enough force along one of these planes, a diamond can chip, crack, or even break. This makes diamonds more susceptible to damage if not properly protected, especially from sharp impacts.
Clarity and Internal Inclusions:

Diamonds that have significant inclusions (internal flaws) or cracks are more prone to damage. Inclusions can weaken a diamond and make it more susceptible to chipping or breaking under pressure.
High-quality diamonds with fewer inclusions tend to have better durability since there are fewer internal flaws that could potentially lead to cracks or fractures.
Cut:

The cut of the diamond also plays a role in its durability. For instance, a diamond with sharp corners (like in a princess cut or emerald cut) is more likely to experience damage if exposed to forceful impacts compared to a diamond with rounded edges, such as in a round brilliant cut.
The way a diamond is set in jewelry can also affect its durability. For example, a diamond set in a prong setting might be more exposed to risks than one set in a bezel setting, where the diamond is surrounded by metal.
Size and Shape:

Larger diamonds, particularly those with thin or pointed areas (like the corners of a princess cut), may be more vulnerable to chipping than smaller diamonds or those with rounder shapes. The girdle (the outer edge of the diamond) can also be a point of weakness if it’s too thin or if it’s exposed to rough handling.
Environmental Exposure:

While diamonds are highly resistant to heat and most chemicals, they can be affected by extreme temperature fluctuations or harsh chemicals. For example, diamonds can fracture if subjected to rapid, extreme temperature changes (such as a sudden drop from a high heat environment to a cold one).
Chlorine bleach and other harsh chemicals can also affect a diamond, especially if the diamond has any inclusions or flaws.
Practical Considerations for Maintaining Diamond Durability:
Setting:
A secure and protective setting is crucial for diamond durability. For example, in a bezel setting, the diamond is surrounded by metal, which offers extra protection from impacts compared to a prong setting where the diamond is more exposed.
Cleaning and Care:
Regular cleaning with warm, soapy water and a soft brush will help maintain the diamond’s appearance and remove dirt, oils, or other materials that might accumulate over time.
Avoid exposing diamonds to harsh chemicals, including household cleaning products or chlorine, as these can cause damage to the diamond’s surface and any metal settings.
Avoid Hard Impacts:
Although diamonds are hard, they can still chip or break if struck with enough force along their cleavage planes. It’s advisable to remove diamond jewelry before engaging in activities where the diamond could be exposed to sudden impacts (e.g., heavy lifting or sports).

Diamond Eight-Cut Faceting (Single Cut Diamond)
The Eight-Cut Diamond, also known as a Single Cut Diamond, is a simpler faceting style primarily used in smaller diamonds, melee stones, and vintage jewelry. It is one of the earliest faceting styles in diamond cutting, designed to enhance brilliance while maintaining a basic, symmetrical structure.

Characteristics of the Eight-Cut Diamond:
Facet Count:

The Eight-Cut Diamond has a total of 17 or 18 facets:
8 crown facets (on the upper part of the diamond)
8 pavilion facets (on the lower part)
1 table facet (flat top surface)
Sometimes a culet (a small facet at the bottom) is added.
This is significantly fewer than a Round Brilliant Cut, which has 57 or 58 facets.
Shape & Appearance:

The Eight-Cut is usually round in shape.
Due to fewer facets, it has a softer brilliance compared to a modern brilliant-cut diamond.
The design focuses on maintaining symmetry while offering a simple sparkle.
Light Reflection:

Since there are only 17-18 facets, the Eight-Cut diamond does not disperse light as much as modern brilliant-cut diamonds.
It produces larger but fewer flashes of light, making it ideal for vintage and antique jewelry.
Uses of Eight-Cut Diamonds:
Melee Diamonds:
Eight-Cut diamonds are commonly used as small accent stones in jewelry settings, such as in pavé, halo, or side-stone designs.
Vintage and Antique Jewelry:
Many older jewelry pieces, especially those from the Art Deco and Edwardian periods, feature Eight-Cut diamonds due to their classic and elegant appearance.
Watches and Fine Jewelry:
High-end watchmakers often use Eight-Cut diamonds as embellishments in luxury watches.

Diamond color dispersion refers to the way light is split into its component colors (a phenomenon called “fire”) as it passes through a diamond. This optical effect is one of the key features that contribute to the visual beauty of a diamond, as it results in the appearance of colorful flashes or “rainbows” when the diamond is moved or light hits it at different angles.

How Color Dispersion Works:
Diamonds have a high refractive index (the measure of how much light is bent or refracted as it passes through the material), which is one of the reasons they sparkle so much. When light enters the diamond, it bends and slows down due to its high refractive index. As the light continues through the diamond, it is then dispersed or split into its component colors, creating the rainbow-like effect.

White light (from the sun or artificial sources) is composed of all colors in the spectrum, and the dispersion effect allows the diamond to separate these colors, showing them as flashes of red, orange, yellow, green, blue, indigo, and violet. The more intense and vivid these flashes, the higher the dispersion.
The degree of dispersion is largely influenced by the diamond’s cut and the quality of its facets. Diamonds that are cut to maximize the path of light through the stone tend to display stronger color dispersion.
Factors Affecting Diamond Color Dispersion:
Refractive Index: Diamonds have a refractive index of 2.42, which is high compared to many other gemstones. This contributes to their excellent ability to refract and disperse light.

Cut of the Diamond: The way a diamond is cut plays a significant role in its ability to disperse light. A well-cut diamond will have facets that are strategically placed to enhance the dispersion effect and maximize brilliance and fire. The angles and proportions of the cut are key factors in how light is channeled within the stone.

Diamond’s Dispersion Value: The dispersion of a diamond is measured by the difference in the refractive indices for red and violet light. Diamonds have a relatively high dispersion value, around 0.044, meaning they separate light into distinct colors. Some diamonds exhibit more noticeable “fire” or color dispersion than others, depending on their cut, size, and overall quality.

Fire and Brilliance in Diamonds:
Fire: The colorful flashes that appear due to dispersion are referred to as “fire.” A well-cut diamond with high dispersion can exhibit spectacular fire, especially when exposed to bright or varying light sources.
Brilliance: Brilliance refers to the white light that is reflected off a diamond’s facets. While dispersion creates colorful flashes, brilliance is the overall white sparkle you see from a well-cut diamond.
Comparison to Other Gemstones:
Diamonds have a higher dispersion than many other gemstones, like sapphires or emeralds, which is one of the reasons they are so visually striking.
Some gemstones, such as garnet or moissanite, have even higher dispersion values than diamonds, meaning they can display even more intense fire, but diamonds are still known for their exceptional balance of brilliance and fire.
Practical Implications for Diamond Buyers:
Fire and Visual Appeal: When selecting a diamond, many buyers are drawn to those that exhibit a strong fire effect due to higher dispersion. Diamonds that show flashes of vibrant color are often seen as more visually appealing.
Cut Quality: A diamond with a high degree of color dispersion is usually the result of an excellent cut. Poorly cut diamonds, even if they are of high quality, may not display the same fire due to improper light dispersion.
Summary:
Color dispersion is the splitting of light into its spectral colors, creating the characteristic “fire” in diamonds.
Diamond fire is a direct result of its dispersion ability, influenced by the diamond’s refractive index and cut.
Diamonds are renowned for their ability to exhibit color dispersion, contributing to their brilliance and visual allure.

The bonds between carbon atoms that make up a diamond are stronger in some planes than others; this means that diamonds are marginally harder at some angles than at others. Diamonds thus have certain planes of weakness along which they can fracture, split or break. Directional hardness is related to the toughness and durability of diamonds.

Diamond directional hardness refers to the varying hardness levels that diamonds exhibit along different crystallographic directions. While diamonds are known for being the hardest natural material, their hardness is not uniform in all directions due to their crystal structure.

Diamond’s Crystal Structure:
Diamonds have a cubic (isometric) crystal structure, where each carbon atom is tetrahedrally bonded to four other carbon atoms, forming a very strong three-dimensional network. However, the strength of these bonds varies depending on the direction in which they are tested.

Directional Hardness in Diamonds:
Hardness Along the Strongest Directions: Diamonds are hardest along the [111] axis, which is the direction along the diagonal of the crystal. This is where the carbon-carbon bonds are the most tightly packed, and the diamond’s crystal lattice is the most resistant to deformation. Along this direction, diamonds are extremely hard and maintain their hardness.

Hardness Along the Weaker Directions: The [100] axis and the [110] axis are considered to be weaker directions in terms of hardness. While diamonds are still very hard along these axes, they are not as resistant to wear and scratching as along the [111] axis. In these directions, the atomic bonding is not as tightly packed as in the strongest directions.

Practical Implications of Directional Hardness:
Cutting and Polishing: When diamonds are cut, the direction of the cut is chosen carefully to exploit the hardest directions of the crystal, ensuring the diamond retains its brilliance and shape. Cutting along weaker directions can make the diamond more prone to chipping or cracking.

Impact on Durability: While diamonds are incredibly durable overall, their directional hardness means that they can be more susceptible to damage if struck along certain axes, especially the [100] or [110] axes. Jewelers and diamond cutters take this into consideration when designing and setting diamonds.

Chipping and Cleavage: Diamonds can cleave or chip more easily along the weaker crystallographic directions, which is why it’s essential to handle diamonds with care during cutting and setting to avoid any damage along these axes.

Summary:
Diamonds are hardest along the [111] axis, and their hardness decreases along other axes such as [100] and [110].
Directional hardness plays a key role in diamond cutting, polishing, and setting, as the crystal’s strength varies depending on the orientation.
Understanding directional hardness is important for maximizing the durability and brilliance of diamonds, especially when they are subject to wear or impact.

Diamond powder is a finely ground form of diamond that is used in a variety of industrial, scientific, and technological applications due to its hardness and unique properties. While diamonds are most commonly known as gemstones, diamond powder has many uses, primarily in fields that require precision cutting, polishing, and abrasives.

Key Uses of Diamond Powder:
Abrasives and Cutting Tools:

Diamond powder is widely used as an abrasive material in industries where precision cutting, grinding, and polishing are required. Its extreme hardness allows it to effectively cut or grind through tough materials such as metals, ceramics, glass, and even other diamonds.
It is often used in the manufacturing of grinding wheels, polishing pads, and cutting tools, where it helps smooth, refine, and shape surfaces.
Polishing and Finishing:

Diamond powder is used for polishing gemstones, including diamonds themselves, to achieve a high level of shine and smoothness. It’s also used for polishing other materials, such as metals and optical lenses, due to its fine abrasive properties.
In the jewelry industry, diamond powder can be used to polish and refine the facets of diamonds and other gemstones, improving their clarity and brilliance.
Laser and Micron Tools:

Diamond powder is used in the production of laser-cutting tools and high-precision micro-tools, where its hardness and fine texture provide exceptional cutting efficiency and durability.
Electronic and Optic Manufacturing:

In the electronics and optics industries, diamond powder is used for polishing lenses and mirrors that require high optical clarity. It’s also used in the manufacturing of semiconductors, where precision is critical.
Nanotechnology and Scientific Research:

Diamond powder has applications in nanotechnology, where its fine particles can be used in research related to nanomaterials, coatings, and surface treatments. It’s also used in scientific equipment and tools that require a high degree of precision.
Diamond Powder Grades:
Diamond powder comes in various grades, depending on factors such as particle size and the specific application. Finer powders are typically used for polishing and delicate finishing work, while coarser powders are used for cutting and grinding.

Synthetic Diamond Powder:
While natural diamond powder can be sourced from industrial diamonds, synthetic diamond powder is also widely available. Synthetic diamonds are produced through high-pressure, high-temperature (HPHT) methods or chemical vapor deposition (CVD) processes. These synthetic powders often have a similar hardness and physical properties as natural diamonds, but they can be produced more cost-effectively and in larger quantities.

Diamond powder is indispensable in industries where extreme precision, cutting, and polishing are needed, making it a versatile and highly valuable material in modern manufacturing.

A diamond gauge is a precise measuring instrument used to assess the dimensions and other critical features of diamonds, such as diameter, depth, and sometimes even the quality of the cut. This tool is especially important in the jewelry and diamond industry to ensure that diamonds meet required specifications and standards.

Types of Diamond Gauges:
Diamond Thickness Gauge:

This type of gauge measures the depth or height of a diamond, from the culet (the tip of the diamond’s pavilion) to the table (the top facet). Thickness gauges are essential for determining the overall proportions and ensuring that the diamond is properly cut for optimal light reflection and sparkle.
Diamond Diameter Gauge:

A diameter gauge is used to measure the diameter of the diamond, particularly for round diamonds. The diameter is an important measurement in determining the overall size and weight of the diamond, and it helps determine the proper setting for the diamond in a piece of jewelry.
Micrometer or Digital Calipers:

In some cases, a micrometer or digital calipers may be used as a diamond gauge. These instruments allow for highly accurate measurements, typically to the nearest hundredth of a millimeter. Micrometers are often used to measure small features, such as the diamond’s girdle thickness or the precision of the cut.
Gauge for Girdle and Table Size:

A specialized gauge can be used to measure the width and thickness of the diamond’s girdle (the outer edge), and the size of the diamond’s table (the flat top surface). These measurements are important because they influence the diamond’s proportions and its ability to reflect light properly.
Facet Gauges:

Some gauges are designed to measure the angles and dimensions of the facets on a diamond. These are important for determining the quality of the cut and ensuring that the diamond will achieve the desired brilliance and fire. They help assess the symmetry of the facets and the overall proportions of the diamond.
Importance of Diamond Gauges:
Accuracy: Diamond gauges ensure that diamonds are accurately measured and comply with the specific requirements set for various cuts and sizes.
Quality Control: By using diamond gauges, jewelers and diamond dealers can ensure that diamonds meet industry standards for proportion and quality, which affects both the aesthetics and the value of the diamond.
Certification and Grading: Diamond gauges are used in diamond grading and certification processes, such as those conducted by gemological laboratories like GIA or DCLA, to provide precise measurements that contribute to the overall grade and value of the diamond.
Overall, diamond gauges are essential tools in the diamond industry for precise measurement, quality control, and ensuring that diamonds meet the necessary standards for both beauty and value.