Buying Diamonds Glossary

Anyone will tell you that Buying Diamonds and other fine jewelry can be a daunting task when you don’t know and understand the language. At the Diamond Experts, we want you to be an informed consumer and diamond investor. Use our comprehensive Glossary to help you quickly understand terms and lingo related to Diamonds.

(Buying Diamonds Glossary A – D)

Acidising: refers to the treatment of diamonds with acids (usually hot) to clean them after mining or after cutting, particularly to remove oxides or polishing residues from surface fissures.

A Jour: is a type of diamond mount that exposes the pavilion to the light and is used in most modern mounts, unlike earlier closed settings.

Baguette: refers to a diamond cut in the shape of a narrow bar, sometimes tapered at one end. It was named after the long French bread loaf.

Baton: is another name for a baguette.

Bearded Girdle: tiny, numerous, hair like fractures extending into the stone.

Bedrock: is the solid rock found under deposits of gravels, silt, sand, soil, etc.

Bezel: occur when the cross-cutter makes the four top corner facets into eight.

Bicycle tyre: refers to a thick girdle.

Blemish: surface imperfection external to the Diamond.

Blocking: is putting on the 16 main facets by the cross-cutter.

Blue ground: is the miner's name for the unoxidized kimberlite in a pipe or other kimberlitic deposit.

Blue-white: is a confusing term often wrongly applied. A blue-white stone should have a faint tinge of blue, even though the description is usually intended to mean colorless. Sometimes it is even applied to stones with a faint tinge of yellow.

Bort: is a very low-grade diamond suitable only for industrial use. Also spelled boart, boort, and bortz.

Bow-Tie Effect: an effect caused by a shadowy area visible in some fancy shapes, caused by light leaking out the bottom of the Diamond.

Brilliance: is the intensity of the white light when a diamond is looked at in the face-up position.

Brillianteerer: is the skilled person responsible for the final stages of putting on and polishing the 40 facets after the cross-cutter's work. It is also spelled brilliandeer.

Brilliant Cut Diamond: see, Brilliant Cut Diamond, Brilliant Cut Diamonds, Round Brilliant Cut Diamonds.

Bruise: inclusions consisting of surface crumbling, often accompanied by tiny, root like feathers .

Bruting: is another name for cutting to fashion the girdle outline of a brilliant cut.

Burned Facet: this facet may appear whitish, or burnt, as a result of the cutter polishing the facet "against the grain".

Calibré Cut: refers to stones that have been cut to standard dimensions for easy setting into standard mounts.

Carat: is the standardized unit of weight for gemstones. One carat is equal to 0.20 of a gram.

Chip: a tiny piece missing, caused by normal wear and tear, or by cutting.

Clean: is used to describe a diamond that has no readily visible inclusions, grade SI and above.

Cleavage: refers to the tendency of a diamond to split along the grain parallel to one of its octahedral faces. It is also a term applied to rough diamonds that have at some time been cleaved from a larger stone.

Cleaver: is the skilled person who cleaves a diamond into two parts.

Closed culet: is the sharp point at the bottom of the pavilion of a brilliant cut, or knife edge on an emerald-cut stone.

Cloud: a group of tiny white inclusions, which result in a milky or cloudy appearance.

Coated Diamond: a diamond colored by a surface coating, which masks the true body-color; the coating may be extensive (entire pavilion, for example), but is more often limited to one or two pavilion facets or a spot on the girdle.

Color: grading color in the normal range involves deciding how closely a stone's body color approaches colorlessness. Most diamonds have at least a trace of yellow or brown body color. With the exception of some natural fancy colors, such as blue, pink, purple, or red, the colorless grade is the most valuable.

Cross-cutter: is the skilled person who grinds and polishes the first 16 facets on a diamond.

Crown: is the upper part of a polished stone above the girdle.

C.S.O.: is the Central Selling Organization, which distributes about 80 per cent of the world's rough gem quality diamonds.

Culet: refers to very small facet on the bottom of the pavilion, parallel to the table. It is also spelled collet and culette.

Cut: is the shape into which a rough diamond is cut and polished.

Cutter or bruter: makes the rough diamond round before it is faceted.

CVD Synthetic Diamond: Synthetic diamonds produced by the chemical vapor deposition (CVD) process. They are grown at very high temperatures, but very low pressures. This growth technique can produce thin, brown to near colorless synthetic diamond crystals that are suitable for faceting for jewelry purposes. Synthetic diamonds grown by this new method differ in their gemological properties from those grown by the traditional HPHT technique.

Diamond paper: is another name for the parcel paper.

Diamond parcel paper: is the specially folded paper in which a diamond is or diamonds are held for carrying, or transporting.

Dispersion: describes the way a diamond breaks up a ray of white light into colour.

Dop: refers to the holder used for a diamond that is being polished. A diamond is held in a solder dop by solder and in a mechanical dop by metal jaws.

(Buying Diamonds Glossary E – H)

Extraction: describes the process of removing diamonds from concentrate.

Extra facet: is an additional small facet usually applied to remove a small blemish most commonly on or near the girdle.

Facet: plane, polished surface of a diamond.

Faceted girdle: refers to a girdle on which small facets have been polished to improve the brilliance of the diamond.

Face up: is the position of a diamond with the table of the stone facing the viewer.

Fancies: are attractively colored diamonds.

Fancy: is a diamond of an attractive color other than white that is suitable for gem use.

Fashioning: general term used to describe the entire process of manufacturing a polished diamond.

Feather: a separation or break due to either cleavage or fracture, often white and feathery in appearance.

Fire: refers to the flashing colors seen when a suitably cut diamond is moved, resulting from its dispersion.

Flaw: an imperfection in a stone.

Flute: is a thin paper used to line the inside of a diamond parcel paper.

Fracture: a crack on the Diamond's surface.

Full-Cut Brilliant: is the correct name for a brilliant-cut diamond with 56 facets plus table and culet.

Girdle: is a sort of rim at the widest part of a diamond by which it is normally set. It is the resulting circumference of the adjoining crown and pavilion angles at the widest part of the stone.

Girdling: describes the way a rough diamond is rounded. It is also another name for cutting and bruting.

Grader: is the skilled person who separates polished diamonds into sizes and quality grades by clarity, color, and accuracy of cut.

Grain: is a name used by cutters and polishers to describe the visible evidence of the crystal structure of a diamond, and will usually determine their procedure.

Grain Center: a small area of concentrated crystal structure distortion, usually associated with pinpoints

Hardness: mineral's resistance to scratching on a smooth surface. Mohs scale of relative hardness consists of 10 minerals, each scratching all those below it in scale and being scratched by all those above it.

(Buying Diamonds Glossary I – L)

Included Crystal: a mineral crystal contained in a diamond.

Inclusion: imperfection internal to the Diamond.

Internal Graining: internal indications of irregular crystal growth. May appear milky, like faint lines or streaks, or may be colored or reflective.

(Buying Diamonds Glossary K – N)

Knot: an included diamond crystal which reaches the surface of a polished diamond.

Laser Drill Hole: a tiny tube made by a laser. The surface opening may resemble a pit, while the tube usually looks needle-like.

Loose Diamond: is a polished diamond that is not mounted.

Luster: refers to the quality of a surface in reflected light. The luster of a diamond is usually described as admantine luster.

Mêlée: are rough stones and shapes under two carats and used loosely for small polished diamonds.

Mixed-cut: is the mixing of two different cuts for one diamond, such as a brilliant cut crown and step-cut pavilion.

Mohs Scale: The ten-point scale of mineral hardness, keyed arbitrarily to the minerals talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond.

Mount or Mounting: is the part of jewelry into which a stone is set.

Natural: is part of the natural surface of a rough diamond left on the girdle by the cutter striving for maximum weight retention.

Navette: is another name for a marquise.

Near-gem: is a quality of rough diamonds between gem and industrial.

Needle: a long, thin included crystal which looks like a tiny rod.

Nick: a notch near the girdle or a facet edge.

(Buying Diamonds Glossary O – R)

Octagon: word describes the process of adding the eight main facets to the top and bottom of a stone, which makes its table octagon-shaped.

Off Make: a poorly proportioned Diamond.

Open culet: is a larger than normal culet.

Open table: is a larger than normal facet.

Open cast or Open Pit: describes mining from the surface.

Opening a diamond: means polishing a window on a rough stone to see inside it.

Pavilion: is the bottom part of a polished diamond below the girdle.

Pinpoints: miniscule spots internal to a Diamond. A cluster of pinpoints can form a cloud.

Pit: a tiny opening, often looking like a white dot.

Point: is the hundredth of a carat, therefore 0.72 carats equal 72 points.

Polished girdle: refers to a girdle that has been polished but not faceted.

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 scaife surface.

Polish Mark: surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.

Quality: measures the degree of excellence of a diamond by its weight, color, clarity and (polished) its perfection of cut.

Rough: is the name given to diamonds before they are cut.

Rough Girdle:  grainy or pitted girdle surface, often with nicks.

(Buying Diamonds Glossary S – V)

Sawyer: is the skilled person who saw diamonds.

Sawable: are the rough diamonds that can be divided by sawing.

Scaife: is also spelled scaive or scaif, and refers to the horizontal turntable or grinding table on which a diamond is polished.

Scratch: a linear indentation normally seen as a fine white line, curved or straight.

Scintillation: refers to the flashing and twinkling sparkle of a diamond when it moved under light. A diamond is always more beautiful in motion because its scintillation depends upon the number of facets visible to the eye when the diamond moves.

Spread Stone: a Diamond with a large table and a thin crown height.

Set: is a diamond or other stone set in a mount.

Skin: is the natural surface of the unpolished diamond.

Sorter: is the skilled person who separates rough diamonds into sizes and grades of quality by shape, color, and clarity.

Star facets: are the eight triangular facets around the table of a diamond that make it star-shaped.

Surface Graining: surface indication of structural irregularity. May resemble faint facet junction lines, or cause a grooved or wavy surface, often cross facet junctions.

Table: is the large facet on the top of the diamond's crown.

Treated Diamond: describes a polished diamond that has been altered to change its appearance, (e.g., by artificial coloration, that is, irradiation).

Twinning Wisp: a cloudy area produced by crystal structure distortion, usually associated with twinning planes.

(Buying Diamonds Glossary W – Z)

Window: is the facet polished on a rough diamond in order to see inside it.

Zales: a national diamond and jewelry chain that offers rings, necklaces, pendants, cameos, earrings and bracelets in a wide variety of designs.