Volume 20, Number 4, October - December 1998

HAS SCIENCE OVERTHROWN THE KING OF GEMS?

Amanda Barnard FGAA, Dip. DT
Integrated Gemmological Solutions, Melbourne

ABSTRACT
Diamond, heralded as the 'adamant' King of Gemstones for centuries, now appears to be coming under attack. Over the past few decades, science has made many breakthroughs and dramatic developments designed to offer new and exotic materials for future use. How does this affect the reign of diamond? Will diamond continue to be the hardest, the strongest, and the most glamorous of gems in the future? This paper outlines some of me potential challengers to diamond, and allows the gemmological community a chance to answer these questions.

THE IDAR-OBERSTEIN GEMSTONE INDUSTRY'S 50TH ANNIVERSARY
A brief history

Prof. Dr Hermann Bank
Deutsch Gemmologische Gesellschaft E.V., Idar-Oberstein, Germany

ABSTRACT
Idar Oberstein Germany's principal gemstone cutting and polishing centre, celebrated its 500th anniversary during 1997. A brief history of the evolution of this still viable industry is presented below.

EXPANDED SCALE REFRACTOMETER
G.A.A. Instrument Evaluation Committee Report

T. Linton, S. Sultman, J. Peters

ABSTRACT
Gemmological refractometers that have been manufactured over the past century have presented gemmologists with a wide range of ever advancing features. 'Value for money' considerations must be of high priority when that all important purchase of a refractometer is made by any working gemmologist. Eickhorst Systems have made a further advance with the release of a refractometer that allows measurement of refractive index with greater accuracy and ease,

For this report the G.A.A's Instrument Evaluation Committee has evaluated the Eickhorst (SR/XS) expanded scale refractometer, and compared its features with those bf other refractometers readily available in the Australian market.

ALASKAN JADE

Paul Howard
Elanora, Queensland

ABSTRACT
Gem quality nephrite known commercially as Alaskan jade is mined from several deposits in north west Alaska's Baird or Jade Mountains. First discovered by native Eskimos, this attractively coloured and patterned nephrite is considered to be a jade of world significance In this paper, the author will summarise present knowledge concerning the history of exploitation, occurrence, economic deposits, methods of recovery, gemmological features, and present status of supply of the nephrite known as Alaskan jade.

SCOTTISH GEM LAB NEWS

Alan Hodgkinson, Scotland

ABSTRACT
A series of short reports from Alan Hodgkinson's Scottish Gem lab on three new gem materials first seen by him during the 1998 Tucson Show. Simple methods for identifying synthetic moissanite, cobalt diffused topaz, and red synthetic diamond are presented.

ALEXANDRITE, EMERALD, RUBY, SAPPHIRE AND TOPAZ IN A BIOTITIE PHLOGOPITE FELS FROM POONA, CUE DISTRICT WESTERN AUSTRALIA

Günter Grundmann, Guilio Morteani,
Technische Univerität München, Germany

ABSTRACT
During 1994 ruby colourless to blue sapphire, and green alexandrite chrysoberyl were discovered as well preserved euhedral tabular or fragmented porphyroblasts together with colourless topaz light green emerald, pink fluorite, margarite, muscovite and quartz at Poona near Cue (Murchison Province, Western Australia). These minerals with possible gem potential occurred in medium grained biotite-phlogopite schists forming the host rock of the well known Poona emerald deposit. This was the first discovery of alexandrite-bearing rocks in Australia.The biotite phlogopite schists belong to a black-wall sequence produced by metasomatic reactions under low grade regional metamorphic conditions between preexisting quartzmuscovite or quartz-topaz greisens and ultramafic bodies. The distinct colour zoning of the corundum, chrysoberyl and beryl porphyroblasis documents variations in chromium supply during their crystal growth.

The fluorescence of both the ruby and alexandrite crystals under long- and short wave ultraviolet radiation (LWUV and SWUV) is light to deep red. The intensity of fluorescence under SWUV is less than under LWUV In daylight the colour of the alexandrite ranges from green to blue-green to blue. Under incandescent light the colour is violet-red.

Until now, very little valuable material suitable for faceting has been found but with ongoing exploration, due to favourable geology, discoveries of more and better quality gem material can be expected.