The facts
What aka Coral actually is
Mineralogically, aka Coral is calcareous skeleton of the deep-water octocoral Corallium japonicum — Mg-calcite CaCO3 with conchiolin, crystallising in the aggregate (trigonal calcite) system.
The colour is caused by carotenoid pigments. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.486-1.658, and the specific gravity sits near 2.60-2.70; cleavage is none.
Where aka Coral comes from
The recognised sources are Kochi Prefecture and the Tosa Bay grounds, Japan, Ryukyu Islands and the Goto grounds, Japan and Taiwan Strait grounds.
Origin affects price in this material, so we name the locality on every quote rather than the country. "African" or "Asian" tells a buyer nothing.
How aka Coral is treated
The highest-valued coral in the trade. Characteristically shows a white core (fu) that cutters work around; dyeing to hide the core is a known fraud. CITES Appendix III (China), so international shipments need a certificate of origin or Appendix III export permit. Japanese harvest is licensed and quota-limited.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What aka Coral is confused with
The usual confusions are Momo coral dyed deeper red, Dyed bamboo coral, Reconstituted coral and Mediterranean Corallium rubrum.
The separation is rarely a matter of opinion: refractive index 1.486-1.658 and specific gravity 2.60-2.70 settle most of it in a minute, and magnification settles the rest.
What aka Coral is used for
Aka Coral is bought by jewellery, carving and sculpture and mineral collecting — and each of those trades wants a different form of the same material.
We quote each application in the unit that trade actually buys in, by the carat, by the block or by the specimen.
Durability and care
Hardness 3-4; cleavage none. 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 aka Coral costs
Indicative pricing for aka Coral is $500-5,000 per gram for fine undyed oxblood; top Japanese cabochons exceed $10,000 per gram.
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 aka Coral treated, and how?
The highest-valued coral in the trade. Characteristically shows a white core (fu) that cutters work around; dyeing to hide the core is a known fraud. CITES Appendix III (China), so international shipments need a certificate of origin or Appendix III export permit. Japanese harvest is licensed and quota-limited.
Where does aka Coral come from?
Kochi Prefecture and the Tosa Bay grounds, Japan, Ryukyu Islands and the Goto grounds, Japan and Taiwan Strait grounds. Origin affects price, so we name the locality rather than the country on every quote.
Is aka Coral 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 aka Coral cost?
Indicatively $500-5,000 per gram for fine undyed oxblood; top Japanese cabochons exceed $10,000 per gram. 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 aka Coral confused with?
Most often Momo coral dyed deeper red, Dyed bamboo coral, Reconstituted coral and Mediterranean Corallium rubrum. A refractive index of 1.486-1.658 and a specific gravity near 2.60-2.70 separate it quickly.
What is aka Coral used for besides jewellery?
carving and sculpture and mineral collecting. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for aka coral?
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 aka coral