CULLINAN DIAMONDS GLOSSARY
Below please find the diamonds glossary terms from S - Z
Saturation: A color's position on a neutral to vivid scale.
Scintillation: Sparkle. The tiny flashes of light noticeable in a diamond when the observer moves his/her head.
Scratch: A linear indentation normally seen as a fine white line, curved or straight.
Semi - Mount: A jewelry setting that has the side stones already mounted, but which contains an empty set of prongs which are intended to mount a diamond center stone that the customer selects separately.
Shape: There are eight common diamond shapes. They are round, marquise, pear, oval, heart, princess/radiant, emerald, and trillion. The round is the most popular (the rest are called “fancy-shaped”). There are also other shapes created and sold by manufacturers.
Single - Cut: A very small round diamond with only 16 or 17 facets, instead of the normal 57 or 58 facets of a full cut round brilliant. Single cuts are occasionally used for pavé jewelry and other jewelry that utilizes numerous small diamonds set closely together.
Spread Stone: A Diamond with a large table and a thin crown height.
Star Facet: One of the eight triangular facets found on the upper crown section (next to the table) of a brilliant-cut diamond.
Step Cut: One of three styles of faceting arrangements. In this type of arrangement (named because its broad, flat planes resemble stair steps), there are three concentric rows of facets arranged around the table and, on the pavilion, there are three concentric rows arranged around the culet. Other styles of faceting arrangements include the brilliant cut (in which all facets radiate out from the center of the diamond toward its outer edges) and the mixed cut (in which either the crown or pavilion of a diamond is cut as a brilliant cut, and the other part of the diamond is cut as a step cut).
Surface Graining: Surface indication of structural irregularity. May resemble faint facet junction lines, or cause a grooved or wavy surface, often cross facet junctions.
Symmetry: Refers to variations in a diamond's symmetry. The small variations can include misalignment of facets or facets that fail to point correctly to the girdle (this misalignment is completely undetectable to the naked eye). Symmetry is regarded as an indicator of the quality of as diamond's cut; it is graded as either Ideal, Excellent, Very Good, Good, Fair or Poor. (Symmetry - see graphic to right)
Table: The flat facet on the top of the diamond. It is the largest facet on a cut diamond.
Table Percentage: The value which represents how the diameter of the table facet compares to the diameter of the entire diamond. So, a diamond with a 60% table has a table which is 60% as wide as the diamond's outline. For a round diamond, gemologists calculate table percentage by dividing the diameter of the table, which is measured in millimeters (this millimeter measurement does not appear on diamond grading reports) by the average girdle diameter (an average of the first two millimeter measurements on the top left-hand side of a diamond grading report). For a fancy shape diamond, table percentage is calculated by dividing the width of the table, at the widest part of the diamond, by the millimeter width of the entire stone (this total width measurement is the second of the three millimeter values in the top left-hand corner of the diamond grading report. Contrary to popular misconception, having a small table percentage (53% to 57%) does not make a round diamond any more brilliant than a diamond with a larger table.
Tone: A color's position on a colorless-to-black scale.
Treated Diamonds: A diamond with a body color induced by some form of artificial irradiation, often in conjunction with controlled heating (known as annealing).
Trilliant Cut: A type of brilliant fancy shape that is triangular. (Trilliant Cut - see graphic to right)
Twinning Wisp: A cloudy area produced by crystal structure distortion, usually associated with twinning planes.
Upper - Girdle Facet: One of the 15 facets found on the lower crown portion of the diamond (abutting the girdle).
