The facts
What gahnospinel actually is
Gahnospinel is classified as spinel group (Zn-bearing spinel), with the composition (Mg,Zn)Al₂O₄. It crystallises in the cubic system.
Colour comes from fe²⁺ with Zn substitution raising RI and density above ordinary spinel, which is also what a laboratory looks at when it is asked whether a colour is natural.
Refractive index 1.725–1.753. Specific gravity around 3.58–4.06. Cleavage: none. Those three numbers separate it from most of what imitates it.
Where gahnospinel comes from
Gahnospinel is produced at Ratnapura and Elahera, Sri Lanka.
That is the whole list. A single source makes supply fragile and makes any claim of a second origin worth questioning.
How gahnospinel is treated
Untreated. The name is a gemmological convenience for zinc-rich spinel; a modern laboratory will normally report it simply as spinel with elevated constants.
Treatment changes value, sometimes by a multiple, so it belongs in the description before the price and not after the sale.
What gahnospinel is confused with
In the trade gahnospinel is most often mistaken for, or substituted by, Ordinary blue spinel, Synthetic spinel or Sapphire.
The separation is rarely a matter of opinion: refractive index 1.725–1.753 and specific gravity 3.58–4.06 settle most of it in a minute, and magnification settles the rest.
What gahnospinel is used for
Demand for gahnospinel comes from jewellery and mineral collecting, which is why one price per carat never covers it.
We quote each application in the unit that trade actually buys in, by the carat or by the specimen.
Durability and care
Gahnospinel is 7.5–8 on the Mohs scale, with none 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 gahnospinel costs
As a guide, gahnospinel trades around $100–$600/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 gahnospinel treated, and how?
Untreated. The name is a gemmological convenience for zinc-rich spinel; a modern laboratory will normally report it simply as spinel with elevated constants.
Where does gahnospinel come from?
Ratnapura and Elahera, Sri Lanka. That is the only commercial source.
Is gahnospinel hard enough to wear every day?
Yes. At 7.5–8 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 gahnospinel cost?
Indicatively $100–$600/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 gahnospinel confused with?
Most often Ordinary blue spinel, Synthetic spinel and Sapphire. A refractive index of 1.725–1.753 and a specific gravity near 3.58–4.06 separate it quickly.
Related stones
Looking for gahnospinel?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
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