The facts
What grossular actually is
The species behind grossular is grossular (garnet group), Ca₃Al₂(SiO₄)₃; it forms in the cubic system.
Varies by variety — V/Cr for green, Fe for orange-brown, none for colourless is responsible for the colour — and the chromophore, not the name, is what decides whether a colour is stable.
On the instruments it reads a refractive index of 1.730–1.760 and a specific gravity of about 3.55–3.73, with none cleavage.
Where grossular comes from
Commercial material comes from Merelani, Tanzania, Jeffrey Mine, Asbestos, Quebec, Canada, Sierra de Cruces, Mexico and Ratnapura, Sri Lanka.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How grossular is treated
Untreated. The species covers tsavorite, hessonite, leuco garnet, mint garnet and massive hydrogrossular, which the trade prices very differently.
We state the treatment on every stone, including when the honest answer is that it cannot be determined. A treatment disclosed is a fact; a treatment discovered later is a refund.
What grossular is confused with
Watch for Tsavorite, Peridot, Demantoid and Green tourmaline — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.730–1.760 and specific gravity 3.55–3.73 settle most of it in a minute, and magnification settles the rest.
What grossular is used for
The trades that buy grossular are jewellery, mineral collecting and carving and sculpture. They do not want the same thing, and they do not pay in the same unit.
We quote each application in the unit that trade actually buys in, by the carat, by the specimen or by the block.
Durability and care
Grossular is 7–7.5 on the Mohs scale, with none cleavage.
With no cleavage plane to worry about, the practical limit is abrasion rather than breakage, and it takes daily wear well.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What grossular costs
Expect roughly $10–300/ct depending on variety, depending on quality.
That is a range, not a quote. Colour, size, clarity, cut and origin move the figure a long way inside it, and the only honest price is one given against a specific stone. Send us what you need and we will price it.
Questions
Is grossular treated, and how?
Untreated. The species covers tsavorite, hessonite, leuco garnet, mint garnet and massive hydrogrossular, which the trade prices very differently.
Where does grossular come from?
Merelani, Tanzania, Jeffrey Mine, Asbestos, Quebec, Canada, Sierra de Cruces, Mexico and Ratnapura, Sri Lanka. Origin affects price, so we name the locality rather than the country on every quote.
Is grossular hard enough to wear every day?
Yes. At 7–7.5 on the Mohs scale with no cleavage plane, it handles daily wear well. The practical limit is gradual abrasion rather than chipping.
How much does grossular cost?
Indicatively $10–300/ct depending on variety. Colour, size, clarity and origin move the price a long way within that, so treat it as a range and ask for a quote against a specific stone.
What is grossular confused with?
Most often Tsavorite, Peridot, Demantoid and Green tourmaline. A refractive index of 1.730–1.760 and a specific gravity near 3.55–3.73 separate it quickly.
What is grossular used for besides jewellery?
mineral collecting and carving and sculpture. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for grossular?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
Ask about grossular