OTHER CUT PARAMETERS

These are other cut parameters that a buyer should pay attention to. Parameters such as extra facets and opens are verified by IDIAM.

EXTRA FACETS

These are usually cut to remove blemishes or certain close to surface inclusions on diamonds. At times these extra facets are also cut to enhance the brilliance of the diamond. These do not usually affect the clarity grade.

Buying Tip:

A perfectly cut piece should not have any extra facets. Rarely do extra facets affect the beauty of a piece, though sometimes it can if the extra facets are really large.

OPENS

Opens are naturals (unpolished material from rough) or inclusions that are reaching to the outer surface of the diamond. Ideally there should be no opens. If an open is a natural, it mean the polishers didn’t polish the rough, mostly as a measure to save weight. If an open is due to an inclusion reaching the surface, it can make the diamond susceptible to splitting if by chance the impact is directly at the opening. IDIAM.com gives grading on open(s) by their location, being either on the crown or on the pavilion side of the diamond.

GIRDLE

The girdle is the outer edge of the diamond,

where the crown (top) meets the pavilion (bottom)

A girdle may be faceted (a series of tiny polished sides going around the diamond), bruted (a single continuous unpolished surface going round the diamond; no longer common), or polished (a bruted girdle that has been polished smooth). Whether a girdle is faceted, bruted, or polished usually has no impact on the value of the diamond. But a thick girdle increases the weight of a diamond but not its spread.

The girdle is described according to its width.

A thick girdle (right) adds weight to a diamond.

The diamond on the right is heavier, yet will appear no larger when set in a ring

Buying Tip

Since any diamond is widest at the girdle, a polisher can add maximum weight to a piece by fattening the girdle. Medium girdle is considered ideal, as thin to very thin girdles while saving weight make the diamond susceptible to breakage by being too thin. If girdle is thick or very thick, you can understand that the polisher has tried to retain more weight than was required to realize more value for the piece.

CULET

The culet is the point at the bottom of a diamond's pavilion. The culet can be a point or a very small facet. The culet size as determined by the GIA, using the following scale:

None, Very Small, Small, Medium, Slightly Large, Large, Very Large.

Buying Tip

Any diamond culet size of Medium or smaller will be invisible to the naked eye, and have no negative impact on a diamond's appearance. However, if a culet is slightly Large or larger, it may allow light entering from the crown to pass straight through the culet facet, reducing the diamond's brilliance. This may also make the culet appear as an inclusion, or create a dead area on the diamond where the light is escaping through the bottom.

HEART & ARROW

The hearts and arrows pattern refers to a symmetrical light pattern visible using a specialized viewer such as firescope in diamonds cut within certain narrow specifications. The intrinsic appeal of the hearts and arrows pattern, with its association to Cupid, is obvious.

Buying Tip

Heart and Arrow is an additional parameter applicable only to Round shape diamonds. The presence of Heart & Arrows is usually not visible to the naked eye. It is only visible under an Hearts & Arrow loupe. Often the presence of the hearts and arrows pattern is taken as confirmation that the diamond is well cut. This is not necessarily true. There is a premium attached to diamonds that exhibit Hearts & Arrows (H&A).

DIAMOND ANATOMY

TABLE

The table is the uppermost, flat surface of a diamond which runs parallel to the plane of the girdle. The table % of a diamond is calculated by dividing the width of the table facet by the width of the diamond.

DEPTH

Depth refers to the distance between the culet and the table when the diamond is viewed from the side. The depth % of a diamond is calculated by dividing the depth by the width of the diamond. The lower the depth %, the larger a diamond of a given carat weight will appear when viewed from above.

CROWN & PAVILLION

Crown is the entire portion of the diamond that sits above the girdle (marked in blue).

Pavillion is the entire portion of the diamond that sits below the girdle (shown in white).

MEASUREMENTS

The length, width, and depth (in that order) of a diamond, expressed in millimeters. The Length and Width are used to calculate the L/W ratio, an important indicator of a diamond's appearance. Also measurements are important for assessing the spread of the diamond.