Nisgabuor is perhaps the oldest continuously mined turquoise mine in the world. Persian turquoise was the first to be mined as early as 7000 BC.
 
This ring is about 27 carats of the highest-grade Ajami Nishabuor turquoise set in the traditional brass setting, size 8, in a traditional box. This example is seldom found outside the many shops in Mashhad Iran. It is not treated and unbacked. It is priced at $2,160. I have assigned a TG of 94 or GG. This grade of Persian sky-blue Ajami has become very rare and more difficult to source. I purchased this ring from Shahriyar Zamansani.