Until 1933, the refractometer and the microscope were the two principal tools in gem testing. Then, B.W. Anderson introduced the hand spectroscope which quickly became the third vital instrument for the UK gemmologist. The publication of Anderson's papers in the mid 1950s alerted gem laboratories worldwide to the importance of this instrument. Today, its use is universal. Anderson and his lifelong colleague, Payne, both of the world's first full-time gemmological laboratory, were the pioneers in recognizing the vast potential of the spectroscope, and "The Spectroscope and Gemmology" is the extensively edited, updated and enlarged version of Anderson's original papers. The distinguished gemmologist R. Keith Mitchell undertook the editing and added chapters on the Pye spectrophotometer and on lasers. He also reproduced new line drawings of spectra in three aspects to accommodate the prism instrument in both the British version and in that favoured by American gemmologists, and in another version as seen through the diffraction grating instrument. Written for gemmologists everywhere, this book is a must for all those involved in the identification of gemstones.