One of the most important minerals on earth and the second most abundant (feldspars being the most abundant), Quartz is also one of the most popular gemstone groups.
Durable and hard, Quartz in its purest form is colourless and known as Rock Crystal. However, trace elements in Quartz produce an array of coloured Quartz crystalline varieties, among them Amethyst, Citrine and Ametrine.
Sources: Quartz is found all over the world but the most prolific sources of Quartz gemstones are Brazil, Madagascar, India, and the USA.
Similar gemstones: There are similar gemstones for each of the Quartz varieties of gemstone, in particular Amethyst and Citrine.
Colour palette: The Quartz colour palette covers the spectrum, from the colourless Rock Crystal through to black and pretty much every colour in between, as well as multi-coloured.
Rock Crystal is the colourless, transparent variety of Quartz.
Tourmalinated Quartz is a colourless Quartz with Tourmaline inclusions, often in the form of long black crystals.
Milky Quartz is the white, translucent to opaque variety of Quartz.
Rutilated Quartz is colourless, with golden yellow inclusions.
Rose Quartz has a soft, milky rose pink colour, ranging from very light pink to medium pink.
Amethyst is the purple variety of Quartz and the most popular and valuable Quartz gemstone.
Citrine is the yellow, orange, or reddish-brown variety of Quartz. Light yellow or lemon yellow Citrine is often called Lemon Quartz in the gem trade.
Ametrine is a combination of purple Amethyst and brownish-yellow Citrine.
Prasiolite, or Green Quartz, is a light green Quartz, which is sometimes also referred to as Green Amethyst, as it is the product of heat treating certain types of Amethyst.
Aventurine is an opaque Quartz that is most often green but may also be grey, orange and brown.
Smoky Quartz is the brown, smoky variety of Quartz, with a colour range from light brown to black.
More information about Quartz: Amethyst is the birthstone for those born in February, while Citrine is one of the birthstones for November (the other being Topaz). When it comes to Wedding Anniversary gemstones, Rose Quartz is the 5th, Amethyst the 6th and Citrine the 13th, while Smoky Quartz is an alternative 70th Wedding Anniversary gemstone. Rock Crystal and Smoky Quartz were once used for crystal balls that disclosed the future to fortune tellers, witches and gypsies.