Tanzanite
Violet-blue, found in one place on earth, and more delicate than it looks
About Tanzanite
Tanzanite is a striking violet-blue, and it is found in only one region of Tanzania. That single source gives it a genuine scarcity story that most coloured gemstones cannot claim.
It is also relatively delicate at Mohs 6 to 7, which makes it better suited to pendants, earrings and occasional rings than to a ring worn every day. That is not a reason to avoid it, but it is a reason to design around it.
Tanzanite is strongly pleochroic, meaning it shows different colours from different angles, typically blue, violet and burgundy. How the stone is cut determines which of those you see most.
The Palette
Swatches are indicative. We will always show you the actual stone in more than one light.
Why Tanzanite Works
A colour with real scarcity
One source, in one region of Tanzania. The supply story is genuine rather than marketing, which is unusual.
The December birthstone
A modern addition to the December list alongside turquoise and zircon, and by far the most requested of the three.
Considerably cheaper than sapphire
For a comparable violet-blue, tanzanite costs far less than a fine blue sapphire of the same size.
Striking at larger sizes
Tanzanite's colour deepens with size, so a larger stone is often disproportionately more impressive.
What to Watch
- Mohs 6 to 7 is not daily-ring territoryBest in pendants, earrings and occasional rings unless carefully protected.
- It has one direction of cleavageA sharp knock in the wrong plane can split it.
- Heat treatment is near-universalAlmost all tanzanite is heated to produce the violet-blue. This is accepted and permanent.
- Avoid ultrasonic cleaning entirelySudden temperature change can crack it.
The Practical Facts
- Hardness
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6 to 7 on the Mohs scale
1 · TalcSofter than quartz, harder than opal10 · Diamond - Toughness
-
Fair; has a cleavage direction
- Suited to
-
Pendants, earrings, occasional rings, protected settings
- Common treatment
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Heat, near-universal and accepted
- Price range
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££ to £££
- Birthstone
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December
Hardness describes scratch resistance, not toughness. The two are different and both matter.
Setting It Well
Low-profile or protected settings only, and a bezel is ideal. Tanzanite suits evening and occasional wear. If a violet-blue engagement ring worn daily is the goal, we would steer you towards a violet-toned sapphire or spinel instead and explain honestly why.
Tanzanite Questions We Are Asked Most
Can tanzanite be used in an engagement ring?
It can, but we would want the wearer to understand the trade. At Mohs 6 to 7 with a cleavage direction, it will not survive a knocked ring as well as sapphire. In a bezel, on a hand that is not doing heavy work, it can be lovely. On a busy hand it is a bad idea.
Is tanzanite really running out?
It comes from a single small area, so the supply is genuinely finite in a way that most gemstones are not. Predictions about exactly when it will run out have been made for decades and should be treated with some scepticism, but the single-source scarcity is real.
Why does tanzanite change colour?
It is strongly pleochroic, showing blue, violet and burgundy from different crystal directions. The cutter chooses which colour faces up, which is why two tanzanites from the same rough can look quite different.
Is heated tanzanite less valuable?
No, because virtually all of it is heated. Unheated tanzanite is brownish and not what anyone wants. The treatment is stable, permanent and entirely standard, and it does not carry the premium question that untreated sapphire does.
The Diamond and Gemstone Guide
Every gemstone stone by stone, plus durability, treatments, ethical sourcing and grading reports.
Round
Pear
Princess
Emerald
Oval
Asscher
Cushion
Marquise
Radiant
Heart
