Kyoto Opal

Kyoto Opal is manufactured, not mined. Kyocera, headquartered in Kyoto, produces it as a synthetic opal impregnated with polymer for added strength. The company says natural opals are brittle and tend to crack when cut, whereas its material is engineered so that it can be cut into almost any shape; it supplies pieces up to about 50 x 50 mm and about 15 mm thick.

GIA notes that Kyocera's traditional polymer-impregnated synthetic opal shows a "chicken wire" or "snakeskin" pattern and a columnar structure under magnification, features diagnostic of synthetic origin. Its stated specific gravity (1.80 to 1.90) is below the value GIA gives for natural opal (about 2.00). GIA also examined a newer Kyocera plastic opal imitation (SG 1.35, RI 1.49) that lacks the snakeskin pattern, shows uniform colour patches about 2 mm across, and burns with an acrid odour when touched with a hot point.

Kyocera gives a Mohs hardness of 4 and a heat resistance of 130 °C, so protect Kyoto Opal from scratches, knocks and heat above that temperature.

In 1987 Karl Schmetzer and Ulrich Henn, writing in GIA's Gems & Gemology, examined the Kyocera play-of-colour products of that time (the "Inamori" material); because the samples contained no water, they proposed calling them opal simulants rather than synthetic opal. For the current Kyoto Opal line, Kyocera says its Kyoto headquarters inspired the colours, which are named after traditional Japanese colours.