WikiJewelry and Gemstone Wiki - Concise dictionary definitions of terms relating to jewelry (jewellery) & gemstones. If you would like to know "what is turquoise?" or "what are minerals?", then Mochishop's wiki can help.
obsidian (n) a type of volcanic glass used as a gemstone. Technically obsidian is a mineraloid as the molten lava - from which it is formed - cools too quickly for crystallisation to happen. Usually it is black or red in colour.
onyx (n) a black variety of chalcedony quartz. Onyx is often banded and can be found in many colours including black, white and brown.
opal (n) a mineraloid gemstone which can be found in an array of colours. Rarely it is red and black; commonly it is white with a colourful opalescent effect. This effect is best produced when opals are cut en cabochon.
opalescence (n) an optical effect produced in opals whereby an iridescent shimmering appears beneath the surface of a stone.
opaque (adj, n) generally speaking, that which is not transparent, impenetrable to light. In context of gemmology, a non-transpararent gemstone such as turquoise or jasper.
organic (adj) gemstones which are derived from living, or once-living, matter. For example, amber, coral, jet and pearl. Cf. Non-organic.
