The facts
What forsterite actually is
Mineralogically, forsterite is olivine group — Mg₂SiO₄, crystallising in the orthorhombic system.
The colour is caused by colourless when iron-free; the familiar peridot green comes from a few percent Fe²⁺. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.635–1.671, and the specific gravity sits near 3.23–3.26; cleavage is imperfect in two directions.
Where forsterite comes from
The recognised sources are Mogok, Myanmar, Åheim, Møre og Romsdal, Norway and Sapat Gali, Kohistan, Pakistan.
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 forsterite is treated
Untreated in gem form. Fractures are sometimes oiled or resin-filled in larger peridot, which is poorly disclosed. Forsterite is also a major refractory and foundry raw material.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What forsterite is confused with
The usual confusions are Peridot, Chrysoberyl, Sinhalite and Green tourmaline.
The separation is rarely a matter of opinion: refractive index 1.635–1.671 and specific gravity 3.23–3.26 settle most of it in a minute, and magnification settles the rest.
What forsterite is used for
Forsterite is bought by jewellery, mineral collecting, heavy industry and technical and precision components — 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, by the specimen or by the tonne.
Durability and care
Hardness 6.5–7; cleavage imperfect in two directions. That combination decides what it can safely be set into.
Hardness is not the whole story. Perfect cleavage means the stone can split cleanly if struck along the wrong plane, whatever its Mohs number, so a protective setting matters more here than the hardness suggests.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What forsterite costs
Indicative pricing for forsterite is Near-colourless faceted material 30–150 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 forsterite treated, and how?
Untreated in gem form. Fractures are sometimes oiled or resin-filled in larger peridot, which is poorly disclosed. Forsterite is also a major refractory and foundry raw material.
Where does forsterite come from?
Mogok, Myanmar, Åheim, Møre og Romsdal, Norway and Sapat Gali, Kohistan, Pakistan. Origin affects price, so we name the locality rather than the country on every quote.
Is forsterite hard enough to wear every day?
With care. It is 6.5–7 on the Mohs scale, which is hard enough, but imperfect in two directions cleavage means it can split if struck at the wrong angle. Use a protective setting and avoid ultrasonic cleaning.
How much does forsterite cost?
Indicatively Near-colourless faceted material 30–150 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 forsterite confused with?
Most often Peridot, Chrysoberyl, Sinhalite and Green tourmaline. A refractive index of 1.635–1.671 and a specific gravity near 3.23–3.26 separate it quickly.
What is forsterite used for besides jewellery?
mineral collecting, heavy industry and technical and precision components. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for forsterite?
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 forsterite