Gem testing

The overall format of previous editions has been maintained and new information has been incorporated in a similar style. This edition has two new chapters, on the manufacture and enhancement of gemstones and the old chapter on the detection of synthetic, imitation and composite stones has been rearranged. In the past decade the development of new synthetics has proceeded apace. Nowadays clean rubies and emeralds need very careful investigation since they could be natural or synthetic. However careful use of the microscope can still elucidate many problems and new instruments are shown in the text.