Mabe' (Or Mobe'): A Japanese term for cultured pearls which are cultured against the shell so that only half a pearl is formed resembling a half-sphere.

Magnesia: Also called periclase, magnesia is a light, solid, white earthy Mineral composed of Magnesium oxide. It is a source of magnesium and is used as a laxative. It takes its name from Magnesia, an ancient city of Asia Minor, and is a mineral ingredient of the philosophers' stone.

Magnesium: A light, silvery-white, moderately hard, malleable, ductile, metallic element which only occurs in nature as a compound with other elements, as found in magnesite, spinel and olivine. In ribbon or powder form magnesium burns with a brilliant white flame, (the so-called magnesium light), which is used in signaling, pyrotechnics, incendiary bombs, or in photography where a strong actinic illuminant is required.

Malachite: A hydrous carbonate of copper, malachite is an opaque green stone characterized by bands of light and dark green which have very pronounced contrast and are often concentric. A source of copper.

Maltese Cross: Named for the Knights of Malta, a group of knights who bore this symbol on their tabards during the Crusades. A Maltese cross has four broad arms of equal length with a V shaped notch cut out of the ends.

Manganese: A gray-white or silvery brittle, metallic, element which resembles iron but is not magnetic. It is found abundantly in the ores pyrolusite, manganite, and rhodochrosite and in nodules on the ocean floor. Manganese is alloyed with iron to form ferromanganese, which is used to increase strength, hardness, and wear resistance of steel.

Manganite: Steel-gray or iron-black crystals composed of manganese oxide. Used as a source of manganese.

Marble: A metamorphic rock composed of calcium carbonate, (like aragonite or coral), or carbonate of lime, (limestone or dolomite, a variety of calcite), which is swirled or clouded with color. It is most often used for architectural and ornamental purposes. The most common variety is white, but it can also be yellow, red, or green.

Marbled: A stone, or other object, with two or more colors swirled together.

Marcasite: A mineral with the same composition as pyrite, (fool's gold), and often called "white iron pyrite", but differing in crystal structure. It can be faceted like a gemstone and is often used in sterling silver jewelry.

Marina chain: A chain composed of small, round, diamond cut links that are designed to lie flat like a curb link chain, but are set very close together.

Mariner link: A chain link resembling a flat oval with a flat bar in the middle of the ring. A figogucci chain is a variant form.

Marquise: (Mar-KEYS, also called a navette). An oval shape gemstone which tapers to a point at both ends, named for the Marquise de Pompadour, Mistress of King Louis XV.

Matinee Length: A necklace which is 30 to 35 inches long.

Matte: With jewelry which has a matte finish the designer uses either a chemical process or an abrasive material to scratch the top layers of the piece creating a dull and non-reflective surface. Also referred to as having a "brushed finish.".

Melanite: A common black variety of garnet composed of iron lime.

Mesh: A sheet of fabric-like woven fine wire, similar to the kind used for screen doors.

Metal: A solid Mineral element that is able to conduct heat and electricity and is pliable under heat or pressure. Common metals include bronze, copper and iron. Metals used for making jewelry, such as platinum, gold, and silver are called "precious metals".

Metallic: There are two basic definitions. A material composed of metal is "metallic", but the term is also used for a material displaying a reflective, shiny, lustrous appearance, like a Metal would.

Mica: A group of minerals consisting of hydrous silicates of aluminum or potassium which are common in igneous and metamorphic rocks. Mica vary in color from pale brown or yellow to green or black and characteristically split into very thin leaves. Sheets of mica used in insulation and electrical equipment because of their resistance to electricity. The transparent forms are used in lanterns, the doors of stoves, etc.

Micromosaic. Ancient Roman mosaic created by using minute pieces of colored glass or stone called tesserae, up to 1400 per square inch. Micromosaics were used for brooches and pins.

Middleman: See Agent.

Milgrain: A raised, beaded edge on a ring done with a special engraver's tool; resembling the edge of a coin.

Milgrain Setting: A milgrain design engraved into the edge of the metal securing a stone in place.

Millefiori: Glass or clay beads with imbedded floral designs. Millefiori means "a thousand flowers" in Italian.

Mine Cut: Differs from the modern Brilliant cut only in its girdle shape, which is square instead of round, a higher crown, smaller table, deeper pavilion, and larger culet, but the number and arrangement of the facets are the same. It is lumpier than the form accepted today. This form of cut surfaced in the early 1800's and began to disappear around the turn of the 20th century.

Mineral: Any inorganic substance; i.e. anything that is not a plant or an animal.

Mineral crystal: see Quartz.

Mint Condition: A piece of jewelry having no signs of wear whatsoever, including no discolored stones. A piece that is in Mint Condition is in virtually the same condition as it was when it left the manufacturer. Considering that vintage jewelry is usually 50 or more years old, and that it likely has been worn, it is obviously quite rare to find a piece that is truly in Mint Condition.

Mohs Scale: A measure of a mineral's hardness and its resistance to scratching invented by Austrian mineralogist, Friedrich Moh. The scale goes from talc (number 1) being the softest, to diamonds as number 10, being the hardest substance known by man. Most gemstones fall in the 6-8 range

Mollusk: An invertebrate animal usually enclosed in a shell, such as an oyster, mussel or clam.

Monoclinic: A system of crystallization wherein two crystal axes intersect obliquely and are perpendicular to the third. See Amphibole.

Moonstone: A transparent, slightly iridescent, milky white variety of feldspar with white or light blue opalescent spots. Moonstone is considered a good luck stone, especially for lovers.

Morganite: A pink variety of beryl found in California, Brazil, and Madagascar named after J.P. Morgan.

Morse: A clasp used by the clergy for fastening garments, such as a cape, in front. It is usually very large, from 12.5 to 17.5 cm in diameter, of various materials and shapes, and decorated in religious themes.

Mosaic: A design created by pressing pieces of stone, glass, or ceramic tile, (called tesserae), in mortar. See also: micromosaics.

Moss Agate: A type of agate displaying a variety of green splotches with a little white or clear. Not much different than Tree agate.

Mother-of-pearl: The pearlescent material on the inside of mollusk shells like abalone, oysters, and mussels. This material can be scraped off, sliced thin, and used as inlay on a variety of jewelry, furniture, etc.

Mothers' rings: A kind of "family jewelry", Mother's rings are rings personalized with their children's birthstones or with birthstones and names.

Mount: To place or fix a stone in the setting. See Mounting.

Mounting: A piece of metal that holds a gem in place.

Mourning Jewelry: Jewelry worn to commemorate the death of a loved one, usually in the form of a ring, brooch, or necklace; widely worn during the Victorian era when the death of Prince Albert plunged Queen Victoria into a lifetime of mourning. See Filigree, Jet, and Jabot Pin.

Muff Chain: A long chain with a clasp used to suspend a lady’s fur muff.