Stone Guide
Tanzanite
Origin: Tanzania (Near Mount Kilimanjaro)
What Makes It Special
Tanzanite is a single-source anomaly. Found entirely in a 4-kilometer strip in the foothills of Mount Kilimanjaro, it's a geological miracle that cannot be synthesized or found elsewhere. This zoisite mineral is famously 'trichroic'—an optical illusion showing deep blue, vibrant violet, and even flashes of burgundy depending on how you view the gemstone. They offer tremendous 'bang for the buck' on size relative to sapphire or emerald.
Required Documentation
While GIA or AGL reports are strongly recommended for significant stones (5ct+), the trade broadly accepts that all tanzanite has been gently heated from its original brownish rough state. The lab report verifies it's genuine zoisite.
Price Guide 2026
⚠️ Almost all tanzanite is heat-treated to remove brownish pleochroism and reveal the stable blue-violet hue. This is universally accepted and priced accordingly. Rare, verified unheated tanzanites (naturally blue) carry massive collector premiums but are exceptionally scarce.
Notable Auction Records
Exceptional Tanzanite and Diamond Necklace (100.00+ carats)
Christie's Geneva
Variable High Estimates
Premium for matching high-saturation suites
Dealer's Notes
Look for 'block D' saturation. Deepest violet-blue with red flashes (known as the 'D-block' color) is the gold standard. Pale lilac tones are far cheaper and less desirable.
Bigger is often better here. Unlike rubies, clean 10ct+ tanzanites exist. They afford a spectacular 'red carpet' look without destroying a client's liquidity.
Always check the cutter's orientation. The cutter had to decide whether to orient the table for maximum weight (often producing more violet) or maximum blue color (often sacrificing weight). The blue orientation is prized.
Be cautious in everyday wear. Tanzanite has a hardness of 6-7 but features perfect cleavage, making it brittle. It is ideal for pendants, statement earrings, or cocktail rings, but should not be an active daily engagement ring.
The single deposit is finite. With strong demand in growing Asian markets, large, deeply saturated stones are legitimate hard assets.
Currently Available