gems, diamond, synthetic diamond, Sumitomo

The distinctive gemological properties of gem-quality synthetic yellow diamonds produced by Sumitomo Electric Industries are described; these commercially grown deep yellow single crystals reach sizes up to 2 carats, though they are currently marketed for industrial use only, typically in pieces up to about 0.40 carat. These synthetic diamonds can be identified by their ultraviolet fluorescence (inert to long-wave, greenish yellow or yellow to short-wave), unusual graining, veining, and color zoning visible under magnification, as well as the absence of distinct absorption bands in their spectra.