Two instruments have been developed at De Beers DTC Research Centre, Maidenhead, to distinguish synthetic diamonds from natural diamonds. The DiamondSureTM enables the rapid examination of large numbers of polished diamonds, both loose and set in jewelry. Automatically and with high sensitivity, this instrument detects the presence of the 415 nm optical absorption line, which is found in the vast majority of natural diamonds but not in synthetic diamonds. Those stones in which this line is detected are "passed" by the instrument, and those in which it is not detected are "referred for further tests." The DiamondViewTM produces a fluorescence image of the surface of a polished diamond, from which the growth structure of the stone may be determined. On the basis of this fluorescence pattern—which is quite different for natural as compared to synthetic diamonds—the trained operator can positively identify whether a diamond is natural or synthetic.