Brilliance – This is the amount of light from the diamond that reaches the eye as a result of total internal reflections from the interior of the diamond and from reflections from the external surfaces of the table and all the other facets.
Bezel Facet – The eight facets on the crown section of a round brilliant cut diamond. The upper point joins the table and the lower point joins the girdle.
Brilliant Cut Diamond – A diamond cut in a round shape and having 58 facets. It is oftentimes referred to as a full cut diamond. A single cut diamond has 17 facets and is usually found in weights ranging from 0.02cts. to 0.005cts.
Carats – A unit of weight for diamonds. 1 carat = 0.200grams or 5 carats = 1.00grams.
Cleavage – When a diamond splits or separates in a definite direction parallel to one of the octahedral planes. A cleavage usually leaves a smooth surface.
Cracks – Irregular splits or separations in a diamond that follow no definite direction and usually leaves a jagged, irregular surface.
Crown – The faceted section of the diamond above the girdle.
Culet The small facet at the bottom tip of the diamond.
Emerald Cut Diamond – A diamond that has a step cutting arrangement. It is square or rectangular with parallel rows of elongated narrow step-up facets on the crown and pavilion. An emerald cut diamond has corner facets at each one of the four corners.
Facets – One of the small polished plane facets put on a diamond. A round brilliant cut diamond has 58 facets. There are 32 on the crown, 24 on the pavilion, the table counts as one and the culet counts as one.
Feather – A jagged, irregular fracture within a diamond. It has the resemblance to a feather and is whitish in appearance.
Fire – The flashes of spectral colour resulting from dispersion that is seen in diamonds. The light leaving the crown facets usually display dispersion.
Gemprint – A ‘fingerprint’ of the diamond taken by recording the internal reflection points created by a harmless low helium laser that passes through the diamond. The pattern is downloaded from the gemmologist’s computer to the international Gemprint data base. It serves as proof positive identification of diamond. Offers ‘peace of mind’ if your diamond ring is left anywhere. Insurance discounts may also apply.
Girdle – The outer edge of the diamond. It usually has a whitish, dull wavy appearance. It may also be polished and transparent.
Heart-Shaped Diamond – A diamond having an overall heart shape. A variation of the pear-shaped diamond with an open ‘v’ slice removed from the central top section.
Inclusion Plot – A colour-coded sketched plotting map of blemishes and inclusions in and on the diamond. The diamond inclusion plot is a method by which you may positively identify your diamond.
Lower-Girdle Facets – One of 16 facets found on the pavilion of the round brilliant cut diamond. The top section of the lower-girdle facet forms lower girdle border.
Marquise Diamond – A style of cutting that has an overall boatshaped formation or “football” like formation. The arrangement and design of the facets is of the brilliant style.
Old-European Cut Diamond – A round shaped diamond cut in the early 1900’s that has a notably high crown, small table, and larger open culet. Priced significantly less than round brilliant cut diamonds.
Oval Cut Diamond – A brilliant style of cutting in which the girdle outline has an oval shape.
Pavilion – The section of the diamond below the girdle.
Pavilion Facet – One of eight facets found on the pavilion of the round brilliant cut diamond. Each pavilion facet comes to a point where it reaches the girdle.
Pear Cut Diamond – A brilliant style of diamond cutting in which the girdle has an overall pear shape.
Points – A unit of weight that is equal to 1/100th. of a carat. Usually used to refer to the weight of smaller diamonds less than .20cts but may be used for any size. A 0.36ct. diamond for example would be equal to a 36 point diamond.
Princess Cut Diamond – This refers to a square or rectangular brilliant cut diamond. The cut does not have any specific number of facets, and both the crown and pavilion have facets similar to the round brilliant style of cutting.
Radiant Cut – The radiant cut has 70 facets, is rectangular in shape and has cut corners. The crown section has a combination brilliant-step cut arrangement and the pavilion section has more of a brilliant styling with a slight step-styling in the upper sections just below the girdle.
Single Cut Diamond – A round shaped diamond with eighteen facets, eight on the crown, eight on the pavilion and the table counts as one and the culet counts as the other one.
Star Facet – One of eight facets found on the upper crown section of the diamond. The top horizontal section of the facet forms the table border and the facet extends approx. half-way down the crown.
Table – The flat horizontal planar surface forming the top of a diamond.
Trilliant Cut Diamond – A curved triangular shaped brilliant cut diamond sometimes referred to as the triangular brilliant cut diamond.
Total Reflection – When a ray of light strikes a diamond and once the ray of light has entered the pavilion and strikes the interior pavilion surface at an angle greater than the critical angle then total internal reflection will occur. This is necessary for the diamond to have brilliance.
Upper -Girdle Facets – One of 16 facets found on the lower crown section of round brilliant cut diamond. The lower section of the facet forms the girdle border and the facet extends approx. half way up the crown.
Addendum Earlier modern brilliant cuts. These diamonds resemble the modern round brilliant cut diamonds. The earlier brilliant cut (sometimes referred to as the transitional cut) has a little larger culet, and a higher crown height. One way to distinguish this cut from the modern round brilliant cut is the fact that the pavilion mains in the earlier modern brilliant cut diamond are about half way from the girdle to the culet. In the modern round brilliant cut diamond they are 2/3’s of the way. The bezel facets are longer in the earlier modern brilliant. They are worth approx. 15% less than modern round brilliant cut diamonds.