Bisbee is a classic turquoise. The history is found in Turquoise in America Part Two, 1910-1990.
 
This cab weighs 4.7 carat and measures 1.5cm X 0.75cm. It is priced at $200 a carat or $940. It is not treated and is backed. I have assigned a TG of 94 or GG. Bisbee of this grade is very rare. I bought this from Bruce Mead who cut the stone. White spot is camera flash.