14K Gold Tanzanite Stud Earrings (1.50 cttw) 30 Day Easy Returns. Jewelry Gift Box Included 14K White Gold Natural Tanzanites are heat treated to produce a range of hues between bluish-violet to violetish-blue. This is done through mild heating in the production process. Due to the permanent nature of this treatment the gemstones do not alter in quality, only in appearance. The total carat weight of the 2 stones is 1.50 CT All our diamond suppliers confirm that they comply with the Kimberley Process to ensure that their diamonds are conflict free.