Buying Tanzanite Jewelry: The rare stone from only one mine in the world
Tanzanite is one of the rarest gemstones on the market – and that's not a marketing statement. It comes exclusively from a single area on Earth: a strip about 7 kilometers long in the foothills of Kilimanjaro in Tanzania. Tanzanite has not been found anywhere else. This means: when this mine is depleted, there will be no more tanzanite. This fact makes it one of the few stones whose rarity is not just claimed, but proven.
What Tanzanite is Mineralogically
Tanzanite is the blue to blue-violet variety of the mineral zoisite. It was discovered in Tanzania in 1967 and marketed as "Tanzanite" by Tiffany & Co. in 1968. In its untreated state, tanzanite is trichroic: it shows different colors depending on the viewing angle – blue, violet, and bronze/brown. In its heat-treated state, which is standard for almost all commercial tanzanites, blue-violet predominates on all axes.
Mohs hardness: 6 to 7 – this limits its suitability for everyday wear. Not ideal for rings subject to intense wear; suitable for pendants, stud earrings, and rings worn occasionally.
Color: The Blue-Violet that Distinguishes it from Sapphire
Tanzanite is often referred to as "cheap sapphire" – this is misleading. Tanzanite has a different color: its blue-violet has a characteristic red hue that sapphire does not possess. In the right light, tanzanite shimmers magenta-violet in a way that no other blue stone can replicate.
The best color in tanzanite: intense blue-violet with a distinct violet component, evenly distributed, without gray zones. Very pale or very dark (almost black) tanzanites are less valuable.
Treatment: Almost Universally Heated
Raw tanzanite is often brown to bronze. Heating it to approximately 500 to 600 °C transforms the brown into the coveted blue-violet. This process has been standard since the stone's discovery and is recognized as acceptable by GIA and other institutions. Untreated natural blue tanzanites exist but are extremely rare.
Conclusion: If a dealer says their tanzanite is untreated and a brilliant blue-violet – that should raise skepticism.
Tanzanite as an Investment?
The finite nature of tanzanite deposits has led some buyers to view it as an investment. The reality is more nuanced: tanzanite has experienced price fluctuations since the 1990s. The question of when the mine will be depleted has been debated for decades. For jewelry and personal enjoyment: excellent. As a pure investment: like all gemstones, with caution.
Tanzanite jewelry in 14k gold at Corelune – with clear stone specifications and treatment transparency.
→ Further reading: Sapphire Jewelry: What Distinguishes it from Tanzanite | Gemstone Ring: Which Stones are Suitable for Everyday Wear
Frequently Asked Questions about Tanzanite
Is tanzanite rarer than diamond?
In terms of origin: yes, significantly. Diamond comes from dozens of mines worldwide. Tanzanite from a single one. However, the actual market price of tanzanite is significantly lower than that of many diamonds – because the global demand for diamonds is much higher.
What is the difference between blue tanzanite and blue sapphire?
Tanzanite has a characteristic violet component that sapphire does not. Compared side-by-side: sapphire is a purer blue, tanzanite is blue-violet with a magenta undertone in certain light. Sapphire (Mohs 9) is significantly more robust for everyday jewelry than tanzanite (Mohs 6–7).
Can tanzanite be worn daily as a ring?
With limitations. Mohs 6–7 makes it more delicate than sapphire or ruby. For office wear and light activities: possible. For intensive physical work: remove it. A bezel setting (metal ring protects the stone laterally) is recommended for tanzanite rings.
How can I identify real tanzanite?
Characteristic blue-violet hue with a red component in the right light, slight dichroism (slightly different color from different angles even after treatment). Synthetic tanzanite exists but is very rare on the market. A GIA certificate is recommended for valuable pieces.
