Iran is known to have the highest quality of turquoise; Arizona ranks next and is also noted for mining the high quality turquoise. South America and China however produce turquoise of moderate grade
Turquoise being hardest and very dense can be cut and polished in their natural state to make jewelry. The alcohol content present in the cosmetic can affect the actual color of turquoise. While buying, ask for written documentation in regards to price and authenticity to avoid fraud.