Striking yet sombre in appearance, many believe onyx gemstones to be exclusively black, however they are found in other variations such as white, red and brown. Onyx gems are 'Chalcedony' stones, meaning they are layered with darker and lighter parallel bands, or a wider band of solid black. Onyx is formed from calcite, when water drips and evaporates from the ends of stalagmites and stalactites in caves. Once the water has evaporated, what's left behind are traces of minerals and calcium carbonate which result in the intricate bands of varying colours.
