Unique Tanzanite Engagement Rings Designed with our Natural Tanzanites and High Quality Full Cut Diamonds. AAA+ Color Tanzanites are among the most beautiful gemstones in the world. These color Tanzanites can be either mix-purple blue or deep blue color. Tanzanites are only mined in Tanzania which makes them even more alluring and appealing. In our our humble opinion, barely any other gemstones can compete with the alluring beauty of Tanzanites when put together with diamonds in a mounting. We custom make these engagement rings after you place an order with attention to detail and high quality craftsmanship. Petra Gems is a small company, but we take high pride in the quality of our products and our unmatched customer service and integrity.