How to Buy a Genuine Tanzanite

Almost all tanzanite sold commercially has been heat-treated to convert its naturally brownish rough into the vivid blue-violet the market wants — a standard, near-universal, and fully accepted practice, unlike the meaningful unheated-versus-heated price gap you'd see in ruby or sapphire. Unheated tanzanite exists but is treated more as a curiosity than a serious value driver, so buyers shouldn't expect — or pay a large premium for — an "unheated" claim the way they would with other corundum gems.

Because tanzanite is trichroic — showing blue, violet, and a brownish-red hue depending on the angle you view it from — cutters orient the rough specifically to maximize the face-up blue-violet color, and that face-up color saturation is the single biggest value driver: a vivid, richly saturated blue-violet (often called "AAA" or "D-block" quality in trade terms, regardless of actual mining block) commands far more than a pale, washed-out, or overly gray-toned stone. Clarity and carat weight follow, with price rising sharply above roughly 3-5 carats since large, clean, well-colored stones become disproportionately scarce from a single, geologically limited deposit.

Tanzanite is relatively soft for a gemstone used in rings, at roughly 6-7 on the Mohs scale, and it can also be brittle along certain cleavage directions — worth factoring into how you set and wear it, favoring protective settings (like a bezel) over exposed prong settings for daily-wear rings, and avoiding ultrasonic cleaners which can stress the stone along its cleavage planes.

For certification specifics, see our Tanzanite certification guide, or check current Tanzanite prices. General authenticity standards that apply across every gemstone we handle are covered on the site-wide Authenticity & Certification page.