Mabé pearls (also known as "cultured blister pearls") are hemispherical pearls particularly suitable for use in brooches and ear jewelry. To produce them, several hemispheres of plastic or wax are glued inside the shell of an oyster. As the animal grows, it covers these hemispheres with layers of mother of pearl. To collect the mabé pearls, the mussels are opened and the pearls removed with a milling machine. The hemispherical shape is removed, the empty space is filled, and the flat back surface is sealed with a mother-of-pearl disc. Most mabé pearls are grown within the South Sea mussels of the Pinctada maxima species. The beads grow to sizes between 10 and 20 mm. Depending on the shape of the artificially inserted shape, pearls can be oval, teardrop-shaped or heart-shaped.

Majorica pearls are imitation pearls. They are industrially manufactured on the Spanish Balearic island of Mallorca and are considered costume jewelry.

Mandarin spessartine is sometimes also known as "mandarin garnet". This especially beautiful type of spessartine occurs in colors ranging from orange to reddish brown and is a member of the garnet group. Spessartine is named after Spessart, a region of Germany where it was first found. Nowadays the mineral is mainly mined in Burma, Brazil, China and Kenya. The best type of spessartine is a variety of mandarin spessartine that is only found in Namibia.

The marquise is a form in which precious stones can be cut. The marquise cut is named after the mistress of the King of France Louis XV. She loved this pointed oval shape and was particularly fond of faceted stones cut into a doubly pointed shape. A stoneis similar to a shuttle and is also grouped under the main title navette ("small ship"). A Marquis diamond has a table and 56 additional facets.

The matrix is the original source of natural stone, the so-called "mother stone" in which crystals grow and where they can be found.

Jewelers use the word "memoir" to describe very personal pieces of jewelry: rings with brilliant-cut diamonds that are presented as gifts to commemorate special occasions. The infinite band of the ring, which has neither a beginning nor an end, adds even greater meaning to the symbolic character of a memory. A fascinating memory ring shape is a simple, unadorned band where brilliant-cut diamonds can be added later as a reminder of special events that occurred throughout life.

Mineralogy is the branch of science that deals with the investigation of minerals. It can be divided into several subordinate parts: crystallography, that is, the science of the form, structure, chemical and physical properties of crystals; special mineralogy, which focuses on the description of minerals according to their genesis, external properties, and distribution; and petrology, that is, the science of stones, which focuses on the genesis and formation of stones and the transformation processes to which they are subjected. Studies of mineral deposits and technical mineralogy complete the spectrum of mineralogical subdivisions.

The Mohs hardness scale is named after its creator, the miner Friedrich Mohs (1773-1839). The scale of the Mohs arranges minerals according to their degree of resistance to mechanical scratches of their surfaces. The scale varies from one to ten. Each mineral of a given degree of hardness is soft enough to be scratched by a mineral at the next higher level and simultaneously hard enough to scratch a mineral on the previous lower level. Hardness minerals 1 are the softest; those of hardness 10 are harder. Gemstones that have scratch resistance (Mohs hardness) of 1 or 2 are classified as soft; buds in grades from 3 to 5 are medium hard; The most difficult ones of grade 6 are described as hard. The values for all minerals and gemstones were determined on the Moh hardness scale. The scale is used worldwide to classify the hardness of stones.

The momme is a Japanese unit of weight for cultured pearls. One momme is equal to 3.75 grams or 18.75 carats. This unit of weight is rarely used in the European pearl trade. Nowadays, the weight of a pearl is typically expressed in grains (a grain is equal to 0.5 grams) or carats. The latter unit is gaining popularity.

Morganite is the pale pink salmon/purple member of the vast beryl family. Because of its color, this mineral is also known as "pink beryl". The name comes from the American collector John Pierpont Morgan. Among other countries, the main sources of the stone include Afghanistan, Brazil and China.

Mother of pearl is produced by soft-bodied animals, the so-called "mollusks". Mollusks include sea mussels and snails that have so-called "epithelial cells". These cells, which produce mother-of-pearl, are responsible for building and growing the shell of mussels. Mother of pearl consists mainly of calcium carbonate, a molecule that contains calcium, carbon and oxygen. Calcium carbonate is found in pearls in the form of aragonite, which covers the inner surface of the shell in countless thin, parallel layers or gathers around a core like the peels of an onion to produce a pearl. Like a mosaic, each of the ultra-thin layers of aragonite is made up of countless plate-like aragonite crystals. The cement that connects these crystals to each other is a horn-like organic substance known as a "conchyne."

Pearls are particularly fascinating today because of their extraordinary diversity. Never before have pearls been available in a wide selection of different colors, shapes and sizes. Each type of pearl has its own color spectrum: Tahitian cultured pearls shine in gray, silver and black shades, often overwashed with a veil of red, blue or green; Freshwater cultured pearls glow white, pinkish and green, and also occur in intense red or lilac hues. When pearls of different colors are tucked into a single necklace, jewelers describe such necklaces as "multicolored" or "harlequin" chains. In addition to combining pearls of different colors, chains often also combine different types of pearls.