Remarkable Hexagram Pattern Produced by a Trapiche Emerald from Colombia
The unique trapiche emeralds from Colombia exert a fascination for many gemologists. A special trapiche emerald weighing...
GUILD Library
Knowledge Repository|40+ Years of Excellence
Research Publications
Academic Papers
Peer-reviewed research, conference presentations, and scholarly contributions advancing gemological science and practice.
A Purple Sapphire Containing Interesting Inclusions: Formation Insights
Recently, the authors examined a cushion-shaped purple sapphire weighing 3.56 ct (Figure 40a). The RIs were 1.762–1.770, yielding a birefringence of 0.008, consistent with sapphire. FTIR spectroscopy confirmed its identification as corundum. The stone displayed strong red fluorescence to long-wave (365 nm) UV radiation (Figure 40b). Chemical analysis by EDXRF spectroscopy revealed appreciable Cr (about 720 ppm) and Fe (approximately 1,200 ppm), along with some Ti (around 230 ppm).
A Pink Sapphire with Questionable Heat Treatment
A pink sapphire weighing over 20 ct was recently submitted to Guild Gem Laboratories, and it presented a particularly ch...
An Unusual Inclusion Formation of Anatase and Rutile in Quartz
The study of inclusions within gem materials provides important insights into their crystallisation processes and the ge...
Periodical Publications
Journals & Periodicals
Annual editions documenting the evolution of gemological knowledge, new treatments, emerging sources, and field research findings.
Visual Documentation
Field Expedition Gallery
Photographic documentation from GUILD's ongoing field operations worldwide—from mining sites to processing centers, capturing the real contexts where gemological knowledge begins.
