Laser Identification: Microscopically smaller superficial inscription created by a laser on a diamond for identification. Relatively easily to remove by polishing.
Marquise Cut: A modification of the brilliant cut, it is a boat shape, elliptical and pointed at both ends. It is sometimes described in old valuations as Navette.
Melee: Small diamonds under .20 carat, usually .10 carat or under, often as small as .8mm in diameter. Can be either fully faceted with 57 facets or single cut.
Mixed Cut: A stone with either the crown or the pavilion cut as a brilliant cut, and the other part as a step cut.
Natural: Part of the rough diamond remaining on a diamond, having survived the cutting process.
Needle: A long, thin included crystal which looks like a tiny rod.
Nick: A notch near the girdle or a facet edge.
Off Make: A poorly proportioned diamond.
Old European Cut: Early round cut, the predecessor to the brilliant cut. The OEC is comprised of chunky facets, a small table, an open culet, and a high crown.
Oval Cut: Cutting shape of a diamond, oval with facets.
Pavillion: The lower portion of the diamond, below the girdle.
Pear Shape Cut: Also referred to as tear drop shape.
Pendeloque Cut: A modification of the brilliant cut, with the stone cut into a pear shape.
Pink: A very rare natural fancy colour. Radiation treated diamonds (not natural) can also create a pink colour variation.
Pink Star: A 59.60 carat fancy vivid pink diamond which set the new world auction record price for any diamond, gemstone, or jewel at Sotheby’s Geneva when it sold for $83.2 million. The new diamanaire owner renamed it “Pink Dream”.
Pit: A tiny opening, often looking like a white dot.
Points: Pts, 1pt is 100th of a carat, or 0.01ct, like a penny to a dollar.
Polish Lines: Tiny parallel lines left by polishing. Fine parallel ridges confined to a single facet, caused by crystal structure irregularities, or tiny parallel polished grooves produced by irregularities in the scraped surface.
Polish Marks: Surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.
Premier: A diamond with a yellowish body colour which is masked by a strong blue fluorescence. The diamond will appear whiter than it actually is, but could have an oily or milky appearance in daylight or fluorescent light. The value of the stone is reduced.
Princess Cut: Normally a square diamond with a faceted base. It is the square equivalent to a round brilliant.
Radiant Cut: A type of brilliant cut fancy shape that resemble a square or rectangle with the corners cut off.
Ratio: A comparison of how much longer a diamond is than it is wide. Used to analyze the outline of fancy shapes. Not applied to round diamonds.
River: Infrequently used reference for the colour of a diamond, ie River = D and E white. River refers to the colour D, exceptionally white.
Round Cut: The most common cut, usually containing 58 facets. Also the most brilliant cut in terms of the most efficient use of light to increase brilliance and fire, hence the name “brilliant”.
Rose Cut: A stone cut with a flat base, with the upper facets cut to a point. Normally encountered in antique jewelry starting with the 17th century, but making a comeback in the last few years.
Scratch: A linear indentation normally seen as a fine white line, curved or straight.
Simulant: Any diamond-like material, either natural or artificial, which is marketed as a look-alike for a natural diamond. ie, glass, zirconium, YAG, GGG, moissanite, etc. Not to be confused with synthetic.
Single Cut: A very small round diamond with only 16, 17, or 18 facets, instead of the normal 57 or 58 facets of a full cut round brilliant. Used mostly for pave jewelry.
Spread Cut: A diamond with a large table and a thin crown height.
Step Cut: One of three styles of faceting arrangements with three concentric rows of facets arranged around the table and three concentric rows around the culet. Baguette cuts (straight or tapered), emerald cuts, and asscher cuts are all step cuts.
Surface Graining: Surface indication of structural irregularity. May resemble faint facet lines, or cause a grooved or wavy surface. They often cross facet junctions.
Synthetic Diamond: Man made, or lab grown, unlike a simulant, has the identical chemical composition and crystal structure as the natural counterpart.
Symmetry: Describing small variations in a diamond’s symmetry, such as misalignment of facets or facet that fail to point correctly to the girdle. An indicator of the quality of the diamond’s cut, graded as either ideal, excellent, very good, good, fair, or poor.
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. A diamond with a 60% table has a table which is 60% as wide as the diamond’s outline.
Tone: A diamond’s colour position on a colourless to black scale.
Top Wesselton: Refers to colours F and G on the diamond colour scale. Some may also call colour F a Top Wesselton+.
Treated Diamonds: Fancy colour treatment: a diamond with a body-colour induced some some for of artificial irradiation, often in conjunction with controlled heating (known as annealing). Other possible treatments of diamonds are: coating, fracture filling, spot bleaching by laser, HPHT (high pressure high temperature) whitening, electromagnetic conduction whitening.
Trilliant Cut: A type of brilliant fancy shape that is triangular.
Twinning Wisp: A cloudy area produced by crystal structure distortion, usually associated with twinning planes.
Van Graff: A diamond simulant made of Yttrium Oxide enhanced CZ. Mohs hardness is 8.7
Wesselton: Originally the name of a diamond mine producing white diamonds. Nowadays a less used reference for the colour of a diamond. Wesselton is H coloured. Top Wesselton refers to colours F and G, and some may also call F a Top Wesselton+.