American Gemological Society. Widely respected in the trade, and considered by many the ultimate authority for cut grading reports.

An exterior imperfection on a diamond, usually a feature of the cutting or polishing of the stone. A diamond may have blemishes and still have an "Internally Flawless" (IF) grading. Most blemishes are so small as to have no affect on the beauty or brilliance of the stone.

Along with life, scintillation, refraction and dispersion, a word used to describe the ability of a diamond to "sparkle" in response to the introduction of light.

An internal feature which runs in the direction of the grain of the diamond. It sometimes extends to the surface of the diamond, or is "healed" inside the diamond. A cleavage is sometimes easily visible, sometimes not. A diamond may be "cleaved," or split in two with a smart, precisely placed blow to a cleavage.

A cluster of microscopic white or crystalline inclusions or pinpoints inside a diamond. Usually visible only with back lighting and under high magnification.

For most preferences, the best color is no color or "colorless". Most diamonds have some lesser or greater degree of yellow or brown color, sometimes so slight that it is virtually imperceptible. Some rare diamonds have very intense or exotic colors (canary, pink, blue, green, purple, or even red) and can be extraordinarily valuable. Colors are designated by letter grades - "D" for absolutely colorless to "Z" for light yellow, and by verbal descriptions for the "fancy" colors.

Laboratory processes ranging from a simple coating or "painting" as it is known in the trade to sophisticated permanent alteration of the presence of certain trace elements found in the naturally occurring diamond. Laboratory certification is your best protection against treated stones.

The bottom most facet or point of a diamond. The culet of some round diamonds may be so pointed they are considered to not be a facet at all.

This is one of the most important of all diamond characteristics, and among the hardest to judge. The proportions of a stone as well as its polish and precision of faceting determine how much of the diamond's potential fire and beauty may be released.

Diamond cutters are paid to maintain a balance between retaining the maximum weight from rough stones and cutting the finest possible diamond at the expense of "yield." Some diamonds are cut exceedingly deep or shallow, or are shaped to conform to the original shape of the rough stone. A poorly made stone tends to result in a higher yield (less waste) from the rough while a better made diamond "wastes" more of the rough. A well-cut round diamond typically weighs only about 40% or less of the original weight of the piece of rough the cutter started with. This is why better cut diamonds command a premium, and why Ideal Cut round diamonds are the most valuable of all.

The way a diamond is cut profoundly influence its sparkle, fire and brilliance, as well as its perceived size and even, to some degree its apparent color. In order to maximize the diamond's brilliance it must be well polished and cut in a geometrically precise manner. This means properly aligning the facets so light will enter the diamond and reflect back through the large top facet, or table of the diamond.

European Gemological Laboratory. Widely respected in the trade offering independent grading certificates.

A common, naturally occurring white or crystalline feather shaped inclusion, which may or may not be visible to the naked eye.

Also known as photoluminescence, the property some diamonds have that makes them glow a certain color (usually blue) when placed in an ultraviolet rich environment. Strong, very strong and sometimes medium blue fluorescence may slightly improve the color appearance of diamonds rated "H" in color or below (I,J,K etc). Such fluorescence in some of the "lower" colors may even enhance the value of these stones. Strong blue fluorescence in diamonds D to F color may impart a very slightly bluish appearance and may, in turn, detract a few percent from the value of those diamonds. Some diamonds with unusually strong blue fluorescence can have a hazy or "milky" appearance. Ashford.com avoids offering such stones to its customers.

An internal or external break or crack which may look like a common flaw. A fracture may have occurred at any time during the natural creation of the stone, or at any time during its use.

An enhancement process by which an inclusion is injected with filler material to mask its presence. A laboratory report such as those offered by Ashford.com is your best protection against fracture filled stones.

Gemological Institute of America, the single most widely accepted diamond authority. An independent, third-party grading service offering diamond grading reports. .

A term used to describe the clarity of the diamond, meaning "Imperfect." A diamond rated I1 usually has inclusions visible to the unaided eye. There are three grades in the I range: I1, I2 and I3.

A term used to describe the clarity of the diamond, slightly more imperfect than I1. There are three grades in the I range: I1, I2 and I3.

A term used to describe the clarity of the diamond, slightly more imperfect than I2. There are three grades in the I range: I1, I2 and I3.

Internally flawless. Free of any internal imperfections to the trained eye at 10 power magnification.

Along with life, scintillation, brilliance, and dispersion, a word used to describe the ability of a diamond to "sparkle" in response to the introduction of light.

Along with life, brilliance, refraction and dispersion, a word used to describe the ability of a diamond to "sparkle" in response to the introduction of light.

A term used to describe the clarity of a diamond with slight inclusions. The GIA recognizes two grades in the SI range: SI1 and SI2. The EGL recognizes a third SI grade, SI3. Well cut diamonds in the SI1 range should be completely clean to the unaided eye when viewed from the top.

Along with life, fire, scintillation, refraction, dispersion, a word used to describe the brilliance of a diamond.

The top and largest facet of a diamond, it is where much of its light both enters and exits the diamond.

The table is the top and largest facet of a diamond through which much of the light both enters and exits. The table percentage is calculated by dividing the average width of the table by the full width of the diamond at the girdle. A table that is too large or too small will reduce the overall brilliance of the diamond. In combination with other factors, the table percentage is a significant component of a diamond's overall cut quality and value.

A term used to describe the clarity of the diamond, meaning very slight inclusions. There are two grades in the VS range: VS1 and VS2. The imperfections in VS stones can be quite difficult to find even with the aid of 10 power magnification.

A term used to describe the clarity of the diamond, meaning very slight inclusions. There are two grades in the VS range: VS1 and VS2. The imperfections in VS stones can be quite difficult to find even with the aid of 10 power magnification.

A term used to describe the clarity of the diamond, meaning very, very slight inclusions. There are two grades in the VVS range: VVS1 and VVS2. Imperfections in VVS stones should be extremely difficult to find even with the aid of 10 power magnification.

A term used to describe the clarity of the diamond, meaning very, very slight inclusions. There are two grades in the VVS range: VVS1 and VVS2. Imperfections in VVS stones should be extremely difficult to find even with the aid of 10 power magnification.