The Blue Gem Turquoise Mine was located in the Copper Basin area southwest of Battle Mountain, Nevada, USA.. Usually a nice blue turquoise but as with most Nevada mines has produced some greens. There is a limited amount of this material available on the market. Enhanced Nevada Blue Gem has been treated using the Zachary process. Zachary process turquoise has been treated with chemicals, and then heated. The process does not alter the properties of the turquoise, but does improve color and stability. The Son and I do all the cutting work we never farm it out. We are Native American gem cutters, we are registered members of the federally recognized Native American tribe Wichita Indians out of Oklahoma. To be clear “100% NATURAL” it is all turquoise no backing was used If it just says “NATURAL” it is natural and backed with JB Weld. The photos in this listing are taken in natural sunlight. Size is Approximate give or take .5 mm Note: In the event of any typos in this listing, the item in the photos is the one or ones you will receive if you purchase this item. PLEASE NOTE: In the event of any typos in this listing, the item in the photos is the one or ones you will receive if you purchase this item. Some countries don't allow gemstones to be shipped to their citizens. Please check with Customs before making your purchases. If you live in one of the countries that don't allow gemstones to be imported and you buy from us, we will issue a refund and not ship the item. We offer a “NO HASSLE” seven-day refund with return shipping paid by the buyer. Our return policy starts when you receive the stone or it hits your PO Box, Buyer Pays return Shipping.