The facts
What sard actually is
The species behind sard is chalcedony, SiO₂; it forms in the trigonal (cryptocrystalline) system.
Iron oxide, in higher concentration and browner tone than carnelian 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 1.530–1.539 and a specific gravity of about 2.58–2.64, with none cleavage.
Where sard comes from
Commercial material comes from Ratanpur, Gujarat, India, Uruguay and Brazil.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How sard is treated
Heated and dyed exactly as carnelian. The sard/carnelian boundary is a matter of tone, not of species, and dealers use the terms loosely.
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 sard is confused with
Watch for Carnelian, Brown agate and Jasper — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.530–1.539 and specific gravity 2.58–2.64 settle most of it in a minute, and magnification settles the rest.
What sard is used for
The trades that buy sard are jewellery, carving and sculpture, decorative objects 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, by the block or by the piece.
Durability and care
Sard is 6.5–7 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 sard costs
Expect roughly $0.50–8/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 sard treated, and how?
Heated and dyed exactly as carnelian. The sard/carnelian boundary is a matter of tone, not of species, and dealers use the terms loosely.
Where does sard come from?
Ratanpur, Gujarat, India, Uruguay and Brazil. Origin affects price, so we name the locality rather than the country on every quote.
Is sard 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 sard cost?
Indicatively $0.50–8/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 sard confused with?
Most often Carnelian, Brown agate and Jasper. A refractive index of 1.530–1.539 and a specific gravity near 2.58–2.64 separate it quickly.
What is sard used for besides jewellery?
carving and sculpture, decorative objects and mineral collecting. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for sard?
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 sard