The facts
What iolite actually is
The species behind iolite is cordierite, Mg₂Al₄Si₅O₁₈; it forms in the orthorhombic system.
Iron; extremely strong trichroism 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 1.542–1.578 and a specific gravity of about 2.57–2.66, with distinct, one direction cleavage.
Where iolite comes from
Commercial material comes from Madagascar, Sri Lanka, India and Tanzania.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
Is iolite treated?
None normally.
Nothing needs disclosing, and nothing about the stone can change after you buy it. If a price looks impossible, the risk is substitution rather than treatment.
What iolite is confused with
Watch for Tanzanite, Sapphire and Amethyst — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.542–1.578 and specific gravity 2.57–2.66 settle most of it in a minute, and magnification settles the rest.
What iolite is used for
The trades that buy iolite are jewellery and mineral collecting. 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 or by the specimen.
Durability and care
Iolite is 7–7.5 on the Mohs scale, with distinct, one direction 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 iolite costs
Expect roughly $10–150/ct, 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 iolite treated?
None normally.
Where does iolite come from?
Madagascar, Sri Lanka, India and Tanzania. Origin affects price, so we name the locality rather than the country on every quote.
Is iolite 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 iolite cost?
Indicatively $10–150/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 iolite confused with?
Most often Tanzanite, Sapphire and Amethyst. A refractive index of 1.542–1.578 and a specific gravity near 2.57–2.66 separate it quickly.
Related stones
Looking for iolite?
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 iolite