Tsavorite
Garnet group · also called Tsavorite garnet, Green grossular
Tsavorite is the green, vanadium- and chromium-coloured variety of grossular garnet, found in a narrow geological belt running through Kenya and Tanzania. It is singly refractive, sold untreated as a matter of course, and rarely clean above two carats — which is why fine larger stones trade close to emerald.
What tsavorite is, and how it differs from emerald
Tsavorite is grossular garnet coloured green by vanadium, usually with some chromium. It is not a species of its own: the species is grossular, and tsavorite is the name the trade gives to the green gem material. Campbell Bridges found it in Tanzania in 1967 and again in Kenya in 1970, and Tiffany & Co. introduced the name in 1974, taking it from Tsavo National Park.
Against emerald it wins on nearly every technical measure and loses on one commercial one. It is singly refractive, so it returns light more brightly; its dispersion of 0.028 is higher, giving noticeably more fire; it is tougher, having no cleavage where emerald cleaves readily; and it is not treated, where almost all emerald is oiled. What it does not have is emerald's four thousand years of name recognition, which is most of what emerald's price is made of.
Why it comes from essentially one place
Tsavorite forms in the Neoproterozoic Mozambique metamorphic belt, in graphitic gneisses where vanadium happened to be available during metamorphism. The productive ground is a narrow corridor along the Kenya–Tanzania border, and despite fifty years of searching almost nothing of consequence has been found outside it.
The deposits are structurally difficult: the gem material sits in isolated pockets and boudins rather than in continuous veins, so mining is a matter of following a geology that keeps stopping. Production is irregular by nature, not by accident, and no amount of investment has made it steady.
The size problem, which is the whole market
Most tsavorite comes out small. Clean material above two carats is uncommon, above five carats it is genuinely rare, and above ten it enters the territory of named stones. The price curve reflects this far more steeply than in most gems: a fine five-carat tsavorite can cost several times the per-carat price of a fine one-carat, where in many species the difference would be modest.
This is worth knowing before you shop. If you want a matched pair or a suite in larger sizes, expect to wait, and expect the wait to be measured in months rather than weeks.
Untreated by default, and why that matters commercially
Tsavorite is one of the very few coloured stones that reaches the market as it came out of the ground. It is not heated, not oiled, not fracture-filled and not diffused — partly because nothing useful is achieved by doing so.
That gives you something rare: a green gemstone where the question of treatment simply does not arise, at a moment when buyers have become wary of enhancement. It is a real selling argument, and it is one that emerald cannot make.
How to tell it from other green stones
The instruments separate it quickly. Tsavorite reads 1.734–1.745 with no birefringence, because it is cubic — so a refractometer that shows a single steady reading with no doubling already excludes emerald, green tourmaline and peridot, all of which are doubly refractive. Its specific gravity of 3.57–3.65 is higher than emerald's and lower than demantoid's.
The confusion that does occur is with chrome tourmaline, which shares the colour and much of the price. Tourmaline is doubly refractive with a birefringence around 0.018, and strongly pleochroic where tsavorite is not — a polariscope settles it in seconds. See chrome tourmaline for the comparison from the other side.
What determines the price
Colour first: the most valued tsavorite is a saturated grass to slightly bluish green, with neither the yellow cast of ordinary grossular nor a tone dark enough to close the stone. Then clarity, since inclusions are visible in a singly refractive stone with no cleavage to hide behind. Then size, which drives the curve harder than in most species. Origin makes little commercial difference; nobody pays a premium for Kenyan over Tanzanian.
What this means if you are buying
Judge the colour away from the display lights and look for the yellow — a slight yellow cast is the most common reason a tsavorite is cheap, and it is easy to miss under warm lighting. Expect no treatment and be suspicious if a seller volunteers a treatment disclosure, because it suggests the stone is not what it is being called. And in sizes above three carats, buy the stone when you find it rather than when you want it.
See what we hold in gems, or tell us what you are looking for.
Is tsavorite a garnet?
Yes. Tsavorite is the green, vanadium-coloured variety of grossular garnet. The species is grossular; tsavorite is the trade name for gem-quality green material, introduced by Tiffany & Co. in 1974 and named after Tsavo National Park in Kenya, near where it was found.
Is tsavorite better than emerald?
Technically, on most measures. Tsavorite is singly refractive so it returns light more brightly, has higher dispersion, has no cleavage where emerald cleaves easily, and is sold untreated where nearly all emerald is oiled. Emerald keeps a far higher price because of name recognition, not performance.
Is tsavorite treated?
No. Tsavorite reaches the market as it came out of the ground: not heated, not oiled, not fracture-filled and not diffused. Nothing useful is achieved by treating it. A seller who discloses a treatment on a stone called tsavorite is describing something else.
Why is large tsavorite so expensive?
The deposits produce mostly small material, held in isolated pockets rather than continuous veins. Clean stones above two carats are uncommon and above five carats genuinely rare, so the price per carat rises far more steeply with size than it does in most gem species.
How do you tell tsavorite from chrome tourmaline?
By double refraction. Tsavorite is cubic, so it gives a single steady refractometer reading around 1.734–1.745 with no birefringence and no pleochroism. Chrome tourmaline is doubly refractive with a birefringence near 0.018 and visible pleochroism, which a polariscope shows immediately.
Tsavorite available now
Nothing in tsavorite is listed at the moment. We buy continuously — tell us the colour, the weight range and the budget and we will come back when something matches.
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