GemstoneTerminology

Gemstone terms and definitions

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Onyx - A semi precious stone that is black or white in color. Onyx belongs to the "chalcedony" family of minerals, which tend to be somewhat porous

Opal - Opals are known for their irridescent, luminous qualities. Opals contain a large amount of water and need to be cared for properly, as experts warn of potential cracking. This semi precious stone contains a wide-ranging mixture of colors that produce a fire-like quality to the stone

Organic - derived from animal or plant matter. Organics related to gems comprise amber, coral, ivory, pearl and tortoiseshell, for example.

Rough - In gemology, this refers to the raw, natural state in which gems are found.

Rutiles - Needle-like inclusions (or foreign matter) within a stone

Semi-precious stone - A stone that is less rare and less expensive than a precious stone, but is still valued for its beauty. Any gemstones valued for their beauty but which are not one of the four "precious stones", (emerald, diamond, ruby or sapphire)

Simulant - A man-made gem having the same appearance, but not the same physical properties, as its natural counterpart. Cubic zirconia has a diamond like appearance, but none of a diamond's properties. *see Synthetic Gemstone

Triplet - A composite gemstone assembled by man consisting of three layers - normally includes a clear protective top layer (quartz or glass) cemented on top of a slice of gem, in turn cemented to a base such as a matrix stone or any other material - opals are often processed in this manner or as doublets. *see Doublet

Synthetic or Lab Grown gemstone - A man-made stone which, unlike a simulant, has the same chemical composition and crystal structure as its natural counterpart. Synthetic stones are often difficult to distinguish from natural stones, and synthetic gems are almost always created with little or no imperfections. Synthetic gemstones are not "fake", since they have exactly the same chemical characteristics as the natural stone, but they are usually flawless and much cheaper than the real thing

Quartz - The family name for naturally occurring crystals composed of silica or silicon dioxide occurring in hexagonal habit. The most common variety is colorless and transparent. The crystalline varieties include: amethyst, ametrine, citrine, rose quartz, and smoky quartz. There are a variety of crypto-crystalline varieties including agate (chalcedony), onyx, sardonyx, carnelian, sard, chrysoprase, bloodstone, jasper.

Zircon - A common mineral occurring in small crystals which is heated, cut, and polished to form a brilliant blue-white gem used as a refractory when opaque and as a gemstone when transparent.. They are not man made stones like cubic zirconia are. Although they are frequently color-treated, zircons occur naturally in clear, yellow, orange, brown and red.