Persian turquoise has a long history. It was the first turquoise to be mined as early as 8000 BCE. While the mines are located in Iran the turquoise is known as Persian.
 
This cabochon weighs 20.4 carats and measures 2.5cm X 1.75cm. It comes from the Nishapur area. It is not treated, not backed and cut in the Persian manner. The cab is priced at $50 a carat or $1020. I have assigned a TG of 81 or HG. I purchased this stone from Shahriyar Zamansani.