More than 25 years of international use have established these Tables as an effective tool in the identification of gemstones, synthetics and imitations and therefore the presentation and layout have remained unchanged. Nevertheless, the content has been partially reworked and updated to include the following new items:
Stones previously given in the Supplement to the Tables (1991) have now been listed in this edition in their appropriate order of increasing refractive indices.
Additionally those minerals meantime found in gem quality are included.
Further a new arrangement and complete range was especially necessary with synthetics as their number has so increased over the years. Details specific to production techniques and diagnostic properties have been listed tabularly.
Additional facts of known mineral groups have been added, e.g. new colour varieties.
An increased number or occurrence of stones previously considered infrequent gave multiple measurements and has led to an expansion of the ranges in physical data.
This present volume contains almost fifty new entries of precious stones and synthetics.
This 3rd edition provides the practising gemmologist with increased and up-dated data on which to rely assuming accurate and systematic identification procedures.