Bisbee turquoise is one of the most famous of all turquoise. It is a byproduct from the Phelps Dodge Lavender Pit copper mine in Bisbee Arizona. The story of Bisbee is found in Turquoise in America Part Two, 1910-1990.
 
This pair of cabochons weigh 10.8 carat and measure 1.5cm X 0.75cm X 3mm. They are  priced at $50,ct or $540. They are not treated and are backed. I have assigned a TG of 84  or HG.I purchased these from Bruce Mead who cut the stone. The white spot is camera flash.