The facts
What andradite actually is
Mineralogically, andradite is garnet group — Ca₃Fe₂(SiO₄)₃, crystallising in the isometric system.
The colour is caused by fe³⁺ gives yellow to brown; Cr³⁺ gives the green of demantoid; Ti⁴⁺ gives the black of melanite. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.880–1.940, and the specific gravity sits near 3.70–4.10; cleavage is none; conchoidal fracture.
Where andradite comes from
The recognised sources are Val Malenco, Lombardy, Italy, Bobrovka, Ural Mountains, Russia, Antetezambato, Madagascar and Tenkawa, Nara, Japan.
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 andradite is treated
Demantoid from Namibia and Madagascar is commonly heated to burn off brown; the treatment is stable and not detectable without inclusion study. Andradite is not dyed or filled.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What andradite is confused with
The usual confusions are Peridot, Chrome diopside, Grossular and Sphene.
The separation is rarely a matter of opinion: refractive index 1.880–1.940 and specific gravity 3.70–4.10 settle most of it in a minute, and magnification settles the rest.
What andradite is used for
Andradite 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
Andradite is 6.5–7 on the Mohs scale, with none; conchoidal fracture 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 andradite costs
Indicative pricing for andradite is Yellow and black material 5–40 USD/ct; Russian demantoid with horsetails 1,000–8,000 USD/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 andradite treated, and how?
Demantoid from Namibia and Madagascar is commonly heated to burn off brown; the treatment is stable and not detectable without inclusion study. Andradite is not dyed or filled.
Where does andradite come from?
Val Malenco, Lombardy, Italy, Bobrovka, Ural Mountains, Russia, Antetezambato, Madagascar and Tenkawa, Nara, Japan. Origin affects price, so we name the locality rather than the country on every quote.
Is andradite 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 andradite cost?
Indicatively Yellow and black material 5–40 USD/ct; Russian demantoid with horsetails 1,000–8,000 USD/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 andradite confused with?
Most often Peridot, Chrome diopside, Grossular and Sphene. A refractive index of 1.880–1.940 and a specific gravity near 3.70–4.10 separate it quickly.
Related stones
Looking for andradite?
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 andradite