A to Z of Diamonds Glossary

Diamonds Index

Round Brilliant Cut Diamond

Macle, Macles	A twinned rough diamond crystal, often triangular and flattish. Also spelt maccle, maccles.
Made	A 'made' stone is one of excellent proportion and finish.
Magnetic, Magnetism	Diamonds are not usually magnetic, although iron and other inclusions can rarely cause a diamond to be magnetic. Synthetic diamonds can be magnetic because of inclusions of iron from the solution from which they were formed. Magnetic nano-diamonds have also been created.
Main Facets	The first sixteen facets to be ground onto rough diamonds, apart from the table and culet, also the main pavilion facets (the first eight on the pavilion).
Marcasite	Iron pyrites (iron sulphide) is often facetted and used as a cheap, but not very effective imitation for diamonds.
Marigold Cut	One of a number of "flower cuts" developed by Gaby Tolkowsky in about 1997 for De Beers.
Marquis	A very common mis-spelling of marquise.
Marquise	Also known as navette or boat shaped, but thousands of illiterate jewellers wrongly spell marquise as marquis!
Mauve	A colour description used for certain pinkish purple diamonds.
Master, Master Stone	Master stones are carefully selected diamonds used by diamond grading laboratories for colour comparison, they are also distributed for use by others who need to grade diamonds accurately. They are usually selected to lie as close as possible to each colour boundary.
Mazel & Broche	Luck and blessing. A traditional Jewish expression used at the conclusion of an agreement to buy and sell diamonds, usually accompanied by a handshake. The seller wishes the buyer good luck, probably because he wants to do repeat business with the buyer, but possibly also because he expects to get paid promptly.
Melée, Mêlée	Slightly woolly term for small diamonds, some consider 8 to 14 points as melée, other anything below 20 points. When sorting rough diamonds for size, it may refer to anything under about a carat.
Millegrain, Milgrain	Literally a thousand grains, setting style where a large number of small grains of metal are raised up to create the diamond setting, a form of rim or bezel setting.
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.
Mined	An expression which has started to appear as a description for natural diamonds as opposed to created or synthetic (real) ones. We have also seen it used misleadingly in comparison with simulants.
Mines	Places where diamonds are extracted from the ground.
Mining	The extraction of diamonds from in-ground deposits, as compared with dredging or other recovery methods.
Mineral	A naturally occurring, homogeneous inorganic solid substance having a definite chemical composition and characteristic crystalline structure, color, and hardness, an ore.
Model, Models, Modelling	When mass or batch production of a piece of jewellery is required, a model-maker will create a master model from which a rubber mould is made for subsequent lost wax casting of the piece in volume. Fashion models are used for photographic shoots for advertising and media promotion of diamonds.
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.
Moh, Mohs	German scientist and geologist who studied minerals and classified them by physical characteristics. He devised a hardness scale, Mohs Scale, which is named after him.
Mohs Scale, Moh's Scale, Mohs' Scale	Simple comparative hardness scale devised by Friedrich Mohs about 1800, and still in use.
Moissan, Henri	French scientist born 1852, discovered carborundum, was awarded the Nobel Prize in 1906 for his work on fluorine, and his development of the electric furnace. In 1892, Moissan theorized that diamonds could be synthesized by crystallizing carbon under pressure from molten iron.
Moissanite	Transparent silicon carbide marketed as a diamond simulant. Named after Henri Moissan.
Molecule	Diamonds are composed of large molecules of carbon atoms with strong bonds in all planes.
Monnickendam	The only remaining major British diamond cutter.
Moonstone	Not only the name of a gemstone, but also the name of a fictional famous diamond in a classic genre-setting detective mystery story by author Wilkie Collins.
Morse, Henry	Henry Dutton Morse, 1826 to 1888, was an early American diamond-cutter, who invented diamond cutting machinery, and produced high quality stones through good proportion many years before Tolkowsky.
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.
Mounting	The process of making a ring or other piece of jewellery into which gemstones will be set. Also an American word for a mount.
Moussaieff	A London jeweller, heading by Shlomo Moussaieff, from Bukhara in Uzbekistan. It has a number of high profile Arab customers, and is notable for having owned a number of record breaking large or famous diamonds, including the Moussaieff Red, and now the Moussaieff Blue.
Muddy	A descriptive term used by some mines or producers in preliminary sorting of rough diamonds.
Mugabe, Robert	Believed to be a major force in smuggled Sierra Leone conflict or blood diamonds, and their laundering.

There are currently over 600 entries in this table.
Over 90 of them have page links to a page on this site. Eventually, we intend to add a more complete description for most entries, each on its own page. Please watch this space!