Ametrine is quartz made up of a naturally occurring mixture of purple Amethyst and yellow Citrine. (The name is derived from AMETyst and ciTRINE). This example has purple amethyst on the outside w/ yellow citrine viewable on the inside. Legend is the Ayoreo natives knew about these bicolor quartz crystals over 500 years ago but written reference to ametrine isn't found until 1925. Today the Anahi mine in Brazil is the only major source of this mineral. I wonder why this stone isn't used for wedding rings? Ametrine is a bargain considering it's size, beauty, and rarity. As w/ most quartz, it's hardness is 7 so it can be faceted just like a diamond. It is a beautiful seamless combination of purple and yellow - kinda reminiscent of the combining of two different people into one married couple. Each rock is unique in it's combination of color. In fact there are many gemstones which are more meaningful to make into a wedding ring than a diamond. Another one of those things that might be logical but won't change.