Royston is the marketing name for turquoise coming from the Royston mineral district which is about 20 miles northwest of Tonopah Nevada. Royal Blue was the oldest claim and today there are as many as 30 turquoise claims selling as Royston or as another name. The history or Royston is found in Turquoise in America Parts One -Three.
 
This cab weighs 33.9 carat and measures 3.5cm X 2cm. It is priced at $10 a carat or $339. It is not treated and is backed. I have assigned a TG of 75 or HMG. I bought the turquoise from Dean Otteson.