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.
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, sometimes having a V-shaped notch cut out of the ends.
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. Marcasites were popular during the 18th & 19th centuries, and right into the Art Deco period. In the days before electricity, they looked like shimmering gemstones in candlelight.
Marquis Cut (pronounced Mar-KEYS): Faceted, elongated oval stone, which tapers to a point at both ends; named for the Marquise de Pompadour, Mistress of King Louis XV (sometimes also called "Navette cut").
Matinee Length: A necklace which is 30 to 35 inches long.
Matte: On jewelry with 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" or "satin" finish.
Micromosaic: An ancient Roman mosaic craft created by using minute pieces of colored glass or stone called tesserae (tiles), applying up to 1,400 per square inch. Micromosaics were used for brooches and pins for Victorian tourists on "The Grande Tour" of Europe.
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. It also has 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.
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.
Mosaic: A design created by pressing pieces of stone, glass, or ceramic tiles, (called tesserae), into mortar.
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.
Mount: To place or fix a stone in a setting.
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