A defect (nick, scratch or abrasion) on the surface of a diamond.

The white light that reflects up through the top of the diamond.

A cluster of small inclusions in a diamond.

The colour tones of the stone. The colour scale ranges from D, meaning fully colourless, to Z, fancy yellow.

The facet on the bottom tip of the diamond. A diamond with no culet has a pointed tip. A diamond with a small to large culet has a flat surface at the tip. Culets can prevent chipping, but are less desirable when of the medium to large range. A diamond with a medium to large culet will appear to have a hole in the bottom when looking down on the stone, through the table.

Used to refer to both the shape of a diamond (round, pear, oval, etc.) and the make (the exact geometric proportions to which a diamond is cut).

Round diamonds that are perfectly proportioned (having depth percentages and table percentages that maximise fire and brilliance) and have high grades on polish and proportions.

Depth refers to the height of a diamond from the culet to the table. The depth percentage listed on the certification indicates the height of the diamond relative to the width measurement (height value, width value). A diamond which is too shallow or too deep will disperse light through the sides or the bottom instead of the top facet.

A diamond with no inclusions visible to the naked eye without the loop.

The flat polished surfaces on a diamond. A round brilliant diamond has 58 facets.

These are small fractures in a diamond. They are usually caused by the tremendous stress that the diamond suffered while it was growing underground.

The coloured light that reflects up through the top of the diamond.

A bluish glow that comes from a stone exposed to ultraviolet light. The effect of fluorescence depends on the combination of the colour of the stone in question and the strength of the fluorescence. Faint fluorescence has very little effect on a stone of any colour. Medium blue fluorescence and strong blue fluorescence can have a positive effect on stones of low colour. (J or worse). The fluorescence actually has the effect of making the stone look closer to near colourless.

The girdle is the narrow belt around the stone, which divides the top portion of the diamond (crown) from the bottom portion of the diamond (pavilion). Girdle is usually expressed as a range, indicating that it may vary from one part of the stone to another. If a girdle has small, flat, polished surfaces on it, it is referred to as "faceted".

A clarity characteristic found within a diamond. Most inclusions were created when the gem first formed in the earth.

Measurements are calculated to the nearest hundredth millimetre and are usually written in this format: length x width x height.

The lower portion of the diamond, below the girdle.

A unit of measurement used to describe the weight of diamonds. One point is equivalent to one-hundredth of a carat.

Refers to the external finish of the facets. An excellent polish reflects the quality of the work the diamond cutter has put into the stone.

Graded according to how precisely the facets are aligned (i.e., the top of the facet should mirror the bottom of the facet). A facet that does not have symmetrical sides will negatively affect how light reflects from the stone.

The largest flat surface on the top (crown) of the diamond. The table percentage refers to how much of the total width is occupied by the table. A table that is either too large or too small will negatively affect how Light reflects up from the surface of the stone.

As with any trade, there is a new language to learn when it comes to diamonds. You don't have to know what each term means but it helps.