The facts
What kornerupine actually is
The species behind kornerupine is kornerupine, (Mg,Fe²⁺)₄Al₆(SiO₄,BO₄)₅(O,OH)₂; it forms in the orthorhombic system.
Green from vanadium, sometimes with Cr and Fe; darker greens are more iron-rich; the rare blue Tanzanian and Kenyan material is Cr-bearing without V or Fe 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 1.660–1.685 and a specific gravity of about 3.25–3.45, with indistinct {110} cleavage.
Where kornerupine comes from
Commercial material comes from Mogok, Myanmar, Taita Hills, Kenya, Ihosy, Madagascar, Ratnapura, Sri Lanka and Harts Range, Northern Territory, Australia.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How kornerupine is treated
Untreated. Strongly trichroic in green, yellow and reddish-brown; chrome kornerupine shows a distinctive purple and green pleochroism. Cat's eye and four-rayed star material from Kenya and Myanmar owes its effects to rutile and graphite inclusions. A collector stone throughout — it has never had a retail market.
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 kornerupine is confused with
Watch for Tourmaline, Enstatite, Peridot, Diopside and Epidote — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.660–1.685 and specific gravity 3.25–3.45 settle most of it in a minute, and magnification settles the rest.
What kornerupine is used for
The trades that buy kornerupine are mineral collecting and jewellery. 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 specimen or by the carat.
Durability and care
Kornerupine is 6.5–7 on the Mohs scale, with indistinct {110} 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 kornerupine costs
Expect roughly $50–400/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 kornerupine treated, and how?
Untreated. Strongly trichroic in green, yellow and reddish-brown; chrome kornerupine shows a distinctive purple and green pleochroism. Cat's eye and four-rayed star material from Kenya and Myanmar owes its effects to rutile and graphite inclusions. A collector stone throughout — it has never had a retail market.
Where does kornerupine come from?
Mogok, Myanmar, Taita Hills, Kenya, Ihosy, Madagascar, Ratnapura, Sri Lanka and Harts Range, Northern Territory, Australia. Origin affects price, so we name the locality rather than the country on every quote.
Is kornerupine 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 kornerupine cost?
Indicatively $50–400/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 kornerupine confused with?
Most often Tourmaline, Enstatite, Peridot, Diopside and Epidote. A refractive index of 1.660–1.685 and a specific gravity near 3.25–3.45 separate it quickly.
Related stones
Looking for kornerupine?
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 kornerupine