The facts
What demantoid actually is
Mineralogically, demantoid is andradite garnet — Ca₃Fe₂(SiO₄)₃, crystallising in the cubic system.
The colour is caused by chromium. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.880–1.889, and the specific gravity sits near 3.82–3.85; cleavage is none.
Where demantoid comes from
The recognised sources are Ural Mountains, Russia, Antetezambato, Madagascar, Erongo, Namibia and Iran.
Origin affects price in this material, so we name the locality on every quote rather than the country. "African" or "Asian" tells a buyer nothing.
How demantoid is treated
Some Namibian and Madagascan material is heated to remove brown.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What demantoid is confused with
The usual confusions are Tsavorite, Peridot and Emerald.
The separation is rarely a matter of opinion: refractive index 1.880–1.889 and specific gravity 3.82–3.85 settle most of it in a minute, and magnification settles the rest.
What demantoid is used for
Demantoid is bought by jewellery and mineral collecting — and each of those trades wants a different form of the same material.
We quote each application in the unit that trade actually buys in, by the carat or by the specimen.
Durability and care
Hardness 6.5–7; cleavage none. That combination decides what it can safely be set into.
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 demantoid costs
Indicative pricing for demantoid is $500–10,000/ct.
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 demantoid treated, and how?
Some Namibian and Madagascan material is heated to remove brown.
Where does demantoid come from?
Ural Mountains, Russia, Antetezambato, Madagascar, Erongo, Namibia and Iran. Origin affects price, so we name the locality rather than the country on every quote.
Is demantoid hard enough to wear every day?
Yes. At 6.5–7 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 demantoid cost?
Indicatively $500–10,000/ct. 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 demantoid confused with?
Most often Tsavorite, Peridot and Emerald. A refractive index of 1.880–1.889 and a specific gravity near 3.82–3.85 separate it quickly.
Related stones
Looking for demantoid?
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 demantoid