The facts
What giant Clam Shell actually is
The species behind giant Clam Shell is dense white shell of Tridacna gigas, T. squamosa and related giant clams, Aragonite CaCO3, crossed-lamellar; it forms in the aggregate system.
Essentially unpigmented; value in the trade is placed on a dense, crack-free, snow-white body 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 1.53-1.68 and a specific gravity of about 2.7-2.9, with none; splits along growth lamellae cleavage.
Where giant Clam Shell comes from
Commercial material comes from South China Sea reefs (Spratly and Paracel Islands), Philippines and eastern Indonesia, Palau, Solomon Islands, and the Great Barrier Reef, Australia and Hainan, China - the carving centre, largely supplied by illegal take.
Different localities give different colour and different clarity, and the trade prices them differently. We state which one.
How giant Clam Shell is treated
CITES APPENDIX II for all Tridacnidae, including fossil and sub-fossil shell in most interpretations. Enormous illegal trade supplies the Chinese beadwork and carving industry, and giant-clam poaching has caused documented reef destruction in the Spratlys; China banned domestic trade in 2017 and then partially relaxed it, so the position is unstable. Frequently bleached and polymer-stabilised. Treat any cheap white 'clam bead' mala from Asia as a CITES risk.
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 giant Clam Shell is confused with
Watch for Bleached coral, Marble and howlite beads and White plastic and resin — these are what turn up sold under this name.
The separation is rarely a matter of opinion: refractive index 1.53-1.68 and specific gravity 2.7-2.9 settle most of it in a minute, and magnification settles the rest.
What giant Clam Shell is used for
The trades that buy giant Clam Shell are carving and sculpture, jewellery and decorative objects. 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 block, by the carat or by the piece.
Durability and care
Hardness 3-4; cleavage none; splits along growth lamellae. That combination decides what it can safely be set into.
Below about 5.5 a stone will be scratched by ordinary household dust, which is largely quartz. That does not make it unusable — it makes it a pendant, an earring or an object rather than a ring worn every day.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What giant Clam Shell costs
Expect roughly $1-20 per gram worked where legal; large carved pieces $500-20,000, but seizure risk is real, 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 giant Clam Shell treated, and how?
CITES APPENDIX II for all Tridacnidae, including fossil and sub-fossil shell in most interpretations. Enormous illegal trade supplies the Chinese beadwork and carving industry, and giant-clam poaching has caused documented reef destruction in the Spratlys; China banned domestic trade in 2017 and then partially relaxed it, so the position is unstable. Frequently bleached and polymer-stabilised. Treat any cheap white 'clam bead' mala from Asia as a CITES risk.
Where does giant Clam Shell come from?
South China Sea reefs (Spratly and Paracel Islands), Philippines and eastern Indonesia, Palau, Solomon Islands, and the Great Barrier Reef, Australia and Hainan, China - the carving centre, largely supplied by illegal take. Origin affects price, so we name the locality rather than the country on every quote.
Is giant Clam Shell hard enough to wear every day?
Not really. At 3-4 on the Mohs scale it is softer than the quartz dust in ordinary household dirt, so it scratches with wear. It suits pendants, earrings and objects better than a daily ring.
How much does giant Clam Shell cost?
Indicatively $1-20 per gram worked where legal; large carved pieces $500-20,000, but seizure risk is real. 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 giant Clam Shell confused with?
Most often Bleached coral, Marble and howlite beads and White plastic and resin. A refractive index of 1.53-1.68 and a specific gravity near 2.7-2.9 separate it quickly.
What is giant Clam Shell used for besides jewellery?
carving and sculpture and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for giant clam shell?
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 giant clam shell