The beautiful yellow Citrine is a variety of Macrocrystalline Quartz – a family of Quartz also shared with other well known gemstones, such as Amethyst, Rose Quartz, Smoky Quartz, Aventurine and Cat’s Eye.
Citrine, the name, comes from the old French word Citrin that means citrus or yellow. The gemstone can be easily mistaken for a Topaz and vice versa. To an untrained eye, both gemstones can look very similar – although a Topaz is generally more expensive.
Citrine owes its yellow color to the presence of iron impurities in the crystal structure of the quartz. There is very little difference between Citrine and Amethyst and therefore by heating the Amethyst the oxidation state of the iron within the stone causes the purple to fade and become the yellow to orange color of the Citrine. This process can be reversed by re-oxidising the stone to turn it back into Amethyst.
Due to the rarity of Citrines, many Citrines are now Amethyst or other stones that have been heat treated. Currently, there appears to be no technology available to test the validity of a Citrine from an Amethyst – as to whether it has been heat treated or not.
Naturally derived Citrine is generally a lighter shade of yellow or orange than heat treated stones, that often turn a darker orange brown color. Since many Citrines are actually Amethysts, it is important to bear this is mind if you wish to buy a Citrine specifically for its Birthstone connections or purported “healing qualities”.
A natural Citrine should have a hardness of around 7 on the Mohs Scale.
If, it is important that the gemstone you buy is a Natural Citrine then you should look for a reputable supplier who can verify whether their stones have been heated treated or not. Brazil is the leader in the production of artificially manufactured Citrines.