The Diamond Certification Laboratory of Australia (DCLA)

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.

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 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).

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.

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.

Eye-Visible Inclusions in Diamonds
An eye-visible inclusion in a diamond refers to an internal flaw or imperfection that can be seen with the naked eye, without the need for magnification. These inclusions can affect the diamond’s appearance, brilliance, and value, making clarity an essential factor when selecting a diamond.

Common Types of Eye-Visible Inclusions
Black Carbon Spots – Dark inclusions that stand out against the diamond’s transparency.
Feathers – Internal cracks that can weaken the diamond and be visible if large or positioned near the surface.
Clouds – Groups of tiny inclusions that create a hazy or milky appearance.
Crystals & Mineral Inclusions – Embedded natural crystals (can be white, black, or colored) visible within the diamond.
Pinpoints – Small white or black spots that, when clustered, can be noticeable.
Needles – Long, thin, needle-like inclusions that may reflect light.
Knots – Inclusions that reach the surface, sometimes appearing as bumps or rough areas.
Cavities – Small holes on the surface of the diamond, sometimes filled with foreign material.

Should You Buy a Diamond with Eye-Visible Inclusions?
For budget-conscious buyers: A well-placed SI1 inclusion can be a great value choice.
For engagement rings or investment pieces: Avoid visible inclusions, as they impact beauty and resale value.
For everyday wear: Ensure inclusions don’t weaken the diamond’s structure.
Would you like help selecting a diamond that looks flawless to the eye while staying within budget?