The Diamond Certification Laboratory of Australia (DCLA)

Describes the girdle of a diamond that has been polished with a series of tiny steps or facets  around the circumference or perimeter.

Any one of the flat, polished surfaces on a diamond.

1 Table

2 Bezel facets

3 Star Facets

4 Upper-Girdle Facet

5 Lower-Girdle Facets

6 Pavilion Main Facets

Any positive diamond colour other than white, brown, or grey with a significant level of saturation. Natural fancy colour in diamonds is rare and valuable; the colour is caused by either impurities or structural abnormalities. Three factors to consider when grading a coloured diamond are body colour, tone, and saturation. Examples of fancy colours, or ‘fancies’: yellow diamonds, orange diamonds, pink diamonds, red diamonds, blue diamonds, purple diamonds, and green diamonds. Examples of non-fancy colours are grey and brown.

Diamond cut into any shape other than a round brilliant cut. Some examples of fancy shape diamonds are: princess cut, emerald cut, oval cut, marquise cut, heart cut, pear cut, and asscher cut diamonds.

Type of cleavage inclusion in a diamond with a wispy, feather-like appearance; the feather-like part extends from the origin of the break. Feathers occur along a cleavage plane, or plane of weakness, in a diamond due to directional hardness; they may appear transparent if viewed head on, or bright white if viewed at a 90° angle.

Qualitative description of the make of a diamond in terms of polish and symmetry.

Visible play of colours created by the break-up of light in a diamond. When light enters a diamond, it reflects off of the pavilion facets and refracts, or bends, into a rainbow of colours as it leaves the crown facets. Also known as dispersion.

Unattractive donut-shaped white ring seen under the table of a round brilliant cut diamond with too shallow a pavilion depth. The ring is caused by the reflection of the diamond’s girdle. Diamonds with a fisheye lack brilliance, and show little life.

Bright, vivid streak of colour found in the glass-like resin filling of diamonds treated by fracture filling.

Trade term used to describe a diamond with a very shallow crown height and/ or pavilion depth. Flat round brilliant cut diamonds with a shallow pavilion tend to show a fish eye. Flat diamonds lack some brilliance and life.

Refers to the clarity of a diamond with no inclusions or blemishes. Flawless diamonds are exceptionally rare.

Natural characteristic which causes many diamonds to glow under ultra violet light (UV), which is abundant in natural daylight and some artificial lighting. Fluorescence is caused by sub-microscopic structures within the diamond. Diamonds can have various colours of fluorescence, with blue being the most common.

Four fundamental criteria on which the quality and value of a diamond are judged: cut, colour, clarity, and carat weight. Two additional factors, transparency and the confidence in a diamond grading certificate are also important value factors. Click here to learn more about the C’s of diamond grading.

Type of break or crack inclusion in a diamond that is irregular, jagged and splintery. A fracture may not follow along a cleavage plane as does a feather, but spreads across the diamond in any other direction.

Treatment to enhance the apparent clarity of a diamond, whereby a glass-like resin is injected into feathers or fractures that reach the surface of the diamond. Feathers are visible when light reflects off of them; by filling them with a resin, light is able to travel through the feather, making it less visible. The resin causes what is known as a flash effect in the treated diamond. Fracture filling is not a stable diamond treatment and is easily altered with heat; click here to learn more.