Natural citrine is a lemon-yellow coloured variety of chrystalline quartz, the name comes from the french for citrus 'citron'. Although it occurs naturally it is rare, most citrine on the market is produced commercially by heat-treating amethyst or smoky quartz. The colours produced range from range from light yellow to golden yellow, to a deeper reddish-yellow and brownish yellow. Colour zoning is common in citrine, seen as lighter and darker shades of colour.
Golden citrine is very popular in jewellery making due to it's beautiful highly saturated colour.
Source locations for natural citrine include: Argentina, Brazil, Madagascar, Myanmar, Namibia, Russia, Scotland, Spain and the USA.
Citrine can only produce bright yellow colouring when a sufficient amount of iron is present in the material. The amount required is rarely found in naturally occurring citrine, hence natural citrines are of pale colours. Most citrine on the market is heat-treated amethyst and colourless smoky quartz.