Pink-to-Red Coral: A Guide to Determining Origin of Color
The characteristic “open” structure of Melithaea ochracaea is evident whether the coral is fashioned with the channels open (above, magnified 15x) or if has been impregnated with a polymer. Photomicrograph by C.P. Smith.
Pink-to-red coral has a long history as an ornamental gem material in jewelry, carvings, and sculptures. However, due to a variety of environmental and legal factors, the supply of high-quality, natural-color coral in this color range has dramatically decreased in recent years— and the quantity of dyed coral on the market has increased. From a study of more than 1,000 natural- and treated-color samples, this article summarizes the procedures that are useful to identify the color origin of pink-to-red coral. A variety of techniques—including magnification, exposure to acetone, and Raman analysis—can determine if the color of a piece of such coral is dyed. Although there are limitations to the use of magnification and acetone, Raman analysis can establish conclusively that the color is natural.
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