The facts
What blue Coral actually is
Mineralogically, blue Coral is aragonitic skeleton of Heliopora coerulea, the only octocoral with a massive aragonite skeleton — Aragonite CaCO3 with iron salts in the organic fraction, crystallising in the aggregate (orthorhombic aragonite) system.
The colour is caused by iron salts bound in the skeletal organic matrix. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.53-1.68 (spot around 1.65), and the specific gravity sits near 2.1-2.5; cleavage is none.
Where blue Coral comes from
The recognised sources are Ryukyu Islands, Japan, Philippines and eastern Indonesia, Great Barrier Reef, Australia and Palau and Micronesia.
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 blue Coral is treated
CITES APPENDIX II (Helioporidae) - permits required. Colour is genuine but frequently deepened with dye or wax, and dyed howlite is sold under the name. Genuinely rare in the gem trade; most 'blue coral' jewellery on the market is dyed sponge coral or dyed bamboo coral. Specific gravity figures vary between references, so treat SG here as indicative.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What blue Coral is confused with
The usual confusions are Dyed sponge coral, Dyed bamboo coral, Dyed howlite and Lapis lazuli and sodalite.
The separation is rarely a matter of opinion: refractive index 1.53-1.68 (spot around 1.65) and specific gravity 2.1-2.5 settle most of it in a minute, and magnification settles the rest.
What blue Coral is used for
Blue Coral is bought by jewellery, mineral collecting and decorative objects — 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 specimen or by the piece.
Durability and care
Blue Coral is 3-4 on the Mohs scale, with none cleavage.
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 blue Coral costs
Indicative pricing for blue Coral is $5-60 per gram worked.
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 blue Coral treated, and how?
CITES APPENDIX II (Helioporidae) - permits required. Colour is genuine but frequently deepened with dye or wax, and dyed howlite is sold under the name. Genuinely rare in the gem trade; most 'blue coral' jewellery on the market is dyed sponge coral or dyed bamboo coral. Specific gravity figures vary between references, so treat SG here as indicative.
Where does blue Coral come from?
Ryukyu Islands, Japan, Philippines and eastern Indonesia, Great Barrier Reef, Australia and Palau and Micronesia. Origin affects price, so we name the locality rather than the country on every quote.
Is blue 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 blue Coral cost?
Indicatively $5-60 per gram worked. 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 blue Coral confused with?
Most often Dyed sponge coral, Dyed bamboo coral, Dyed howlite and Lapis lazuli and sodalite. A refractive index of 1.53-1.68 (spot around 1.65) and a specific gravity near 2.1-2.5 separate it quickly.
What is blue Coral used for besides jewellery?
mineral collecting and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for blue 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 blue coral