Vir Jewels 1 CT 5-Stone Oval Cut Tanzanite Ring in 10K White Gold in Size 7 Save An Additional 20% USING COUPON CODE: ZBM72EGW 90 Day Warranty. Jewelry Gift Box Included 10K 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.