Carico Lake is the marketing name for turquoise from the Aurora claim in Carico Lake Valley Nevada. The story is found in Turquoise in America Part Two. 1910-1990.
 
This cabochon weighs 45.8 carat and measures 3cm X 2.5cm X 7mm. It is priced at $20 a carat or $916. It is not treated and is backed. I have assigned a TG of 86 or VHG. It shows the characteristic green of Carico Lake and what looks to be a spot of very rare Faustite (overexposed). I purchased this stone from Bob Brucia.