Persian turquoise has the oldest recorded history of mining dating to as early as 5000BC. The mines at Nishabur have been in operation for hundreds of years.
 
This cabochon weighs 32.1 carat and measures 2.5cm X 1.25cm X 1cm and is priced at $80 a carat or $2,568. It is not treated and unbacked. I have assigned a TG of 90 or VHG. I purchased this stone from Shahryar Zamansani who purchased from the miners at Nishabur.