Mauve

A color description used for certain pinkish purple diamonds.

Millennium Star

A large famous diamond, made even more famous by the audacious attempt to steal it and other diamonds from the Millennium dome exhibition.

Milky

Some over-fluorescent diamonds have a cloudy or milky appearance, especially in ultra-violet light or daylight.

Mine

A place where diamonds are extracted from the ground, by either open cast or deep pit mining.

Minning

The extraction of diamonds from in-ground deposits, as compared with dredging or other recovery methods.

Mine Cut Diamond

An early form of the brilliant diamond with a squarish-shaped girdle, high crown, small table, deep pavilion, and very large culet.

Modern Brilliant Cut

A diamond normally with 58 facets including the culet, polished using relatively modern theory, but not necessarily ideal or near ideal proportions, usually round unless otherwise stated.

Modified Brilliant Cut

A diamond cut in a shape or style other than round, such as oval, pear, marquise, heart, princess, radiant, or trilliant. Could also be applied to round stones based on the brilliant cut.

Mohs Scale

The 10-point scale of mineral hardness. Diamond scores 10 on Mohs Scale. The diamond is the hardest of all known natural substances.

Mount

A piece of jewellery into which a diamond is set.

Mounter

Person who makes the piece of jewellery into which gemstones will be set by a setter.

Muddy

A descriptive term used by some mines or producers in preliminary sorting of rough diamonds.

Natural

These blemishes can be found on some polished diamonds when some of the rough is left on the diamond. This is often done so the cutter can maximize weight in a diamond.

Needle

A thin, sharp looking inclusion in a diamond.

Nexus

Diamond Nexus Labs of Franklin, Wisconsin misleadingly describe diamond stimulants on their website as synthetic diamonds, and make numerous other dodgy claims.

Nickel

Used as a solvent and catalyst in production of synthetic diamonds.

North Light

Diamonds have traditionally been sorted in north light, often before midday, as this is considered to be a consistent color, although special standardized diamond sorting lighting is now available and in common use.

Octahedron

A solid figure having eight sides or faces. A rough diamond with this approximate shape. The commonest crystal formation of diamond.

Old Cut

Any cut, usually round, predating the modern brilliant cut in style.

Old European Cut Diamond

The earliest known form of brilliant cut diamond with a very small table, heavy crown and large depth.

One Carat

A weight of one fifth of a gram. Any diamond of this weight.

Open Culet

Culet which has been polished into a facet rather than being left as a point.

Oval

A fancy shape of diamond, usually a modified brilliant cut.

Palladium

Important jewellery metal, used in high quality alloys of platinum and white gold.

Pave

From French, literally paved. Diamonds are other gemstones set in such a way that they substantially cover a surface of a piece of Jewellery.

Pavilion Angle

The angle between the main pavilion facets and the girdle. In diamond cutting and proportion, this is the single most important dimension, and should be around 40.75° to 41°.

Pavilion Facet

Any of the facets on the pavilion of a diamond, but usually referring to the main pavilion facets, as distinct from the lower girdle facets.

Pavilion

The bottom portion of a diamond, from the girdle (the thickest part around the stone) to the culet.

Phosphorescence

Some diamonds and other gemstones and minerals continue to glow or emit visible light for a period of time after exposure to visible, ultra-violet or other light, after the light source has been removed.

Photoluminescence

The emission of visible light by a diamond due to the incidence of light of a different wavelength, including fluorescence and phosphorescence.

Platinum

Silvery gray precious metal often used for setting or mounting high quality diamonds as Jewellery.

Pin Point

A very small white dot on the surface of the stone. By far, the most common flaw that can be found on a diamond.

Polish

The final smoothness of the surfaces of a diamond. An excellent polish will result in a lower-weight stone, so most diamond cutters will make tradeoffs.

Polish Mark

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

Prong

American word for claw, as in gem setting.

Proportion

The consideration of the overall shape of a diamond taking each part in relation to all other parts. An important quality element for diamonds.

Purity

Another word of Clarity.