Ametrine is a naturally occurring variety of quartz. It is a mixture of Amethyst and Citrine, the purple colors being Amethyst and the yellow to orange colors being Citrine. Ametrine is sourced worldwide, most commonly in Brazil and Bolivia. The color of the zones visible within Ametrine are due to differing oxidation states of iron within the crystal. The different oxidation states occur due to there being a temperature gradient across the crystal during its formation. Ametrine is said to be the complete balance of the properties of Amethyst and Citrine. Natural Ametrine is considered to be a rare variety.