Dyed Coral

(via Gems & Gemology, Spring 2007) Here is what Maggie Campbell Pedersen has to say about dyed coral.

I was surprised that no mention was made of Bamboo coral, belonging to the genus Isis, as, in my experience, that is the coral type that we frequently encounter in modern, lower-end jewelry and carvings. It is available at every fair, market, and in the less exclusive shop.

White it is true that expensive or antique red coral items tend to be Corallium corals—dyed or not—there are masses of bamboo coral about that are simulating red Corallium coral. Bamboo coral also has the striations that are typical of Corallium corals, but whereas the Corallium’s striations are very fine—0.25 to 0.5mm apart—those of bamboo coral are ~ 1mm apart, so the two corals are easily distinguishable. Further, bamboo coral items often show a hint of the nodes of horny material that separate the internodes of calcium carbonate. These do not occur in Corallium corals and so help with identification. As regards color, bamboo coral does not naturally occur in red, so any bamboo coral encountered in red (and quite often orange) is dyed, and therefore does not need to be tested. I feel that to omit mention of bamboo corals altogether could lead your readers to believe that any coral displaying striations is a Corallium coral which needs to be tested. This is not the case.