A beautiful Montana sapphire that shows stronger blue color in natural daylight. (excerpt)

Asscher Cut Sapphire, Rock Creek, Montana, U.S.A., 0.85 Carat cts - International Gem Society

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Asscher Cut Sapphire, Rock Creek, Montana, U.S.A., 0.85 Carat cts

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Corundum

Sapphire

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		In 2012, Donald Clark retired and passed along stewardship of the IGS to Seth and Lisa Rosen. Seth and Lisa were longtime members of the IGS.  Seth is a gem collector and active Internet entrepreneur, who had already spent a great deal of time in the custom jewelry business. He founded <a href="https://www.custommade.com">CustomMade, the world’s largest online custom jeweler</a> and also operates <a href="https://www.ganoksin.com">The Ganoksin Project, a technical resource website for bench jewelers and jewelry manufacturers</a>. Seth and Lisa felt strongly that the IGS needed to remain a cost-effective, accurate, and comprehensive resource for all those interested in gemology.  IGS is our passion, and it is a family business.
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Seth and Lisa Rosen

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<div class="intro-paragraph__content">
		Donald Clark, CSM founded the International Gem Society in 1998. Donald started in the gem and jewelry industry in 1976. He received his formal gemology training from the Gemological Institute of America (GIA) and the American Society of Gemcutters (ASG). The letters &#8220;CSM&#8221; after his name stood for Certified Supreme Master Gemcutter, a designation of Wykoff&#8217;s ASG which has often been referred to as the doctorate of gem cutting. The American Society of Gemcutters only had 54 people reach this level. Along with dozens of articles for leading trade magazines, Donald authored the book <em>Modern Faceting, the Easy Way</em>.
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Donald Clark, CSM IMG

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<div class="intro-paragraph__content">
		Jeffery Bergman was a contributor to the IGS long before Seth and Lisa were involved.  Aside from Don Clark, he is the longest-standing contributor to IGS.  In honor of his decade of friendship and support, Jeffery holds the honorary title of Vice President, Emeritus – International Gem Society.  He is, and always has been, a fully pro-bono contributor and maintains no financial interest in IGS.
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</p></div>
<p>With humble roots from a non-gem trade family, as a lapidary hobbyist, Jeffery cut and polished his first gemstone at the age of fourteen launching him on a lifelong career which has taken him to more than 70 countries, and every continent except Antarctica. With 5 decades of broad-based experience in natural gemstones, diamonds and fine jewelry, in 2020 Jeffery founded <a href="https://www.eighthdimensiongems.com" target="_blank" rel="external noopener" data-wpel-link="external">Eighth Dimension Gems</a> (formerly Primagem) in Bangkok, Thailand, where he has lived for over 30 years.</p>
<p>Jeffery’s formal gemmological training was accomplished at the prestigious <a href="https://www.ssef.ch/courses/" target="_blank" rel="external noopener" data-wpel-link="external">Swiss Gemmological Institute</a> in Basel, Switzerland where he passed requisite exams for his SSEF Basic Gemmology (BGC) and SSEF Basic Diamonds (BDC) Diplomas. Additionally, he completed SSEF’s Advanced <a href="https://www.gemsociety.org/article/pearl-jewelry-and-gemstone-information/" data-wpel-link="internal">Pearls</a> (ATC), Advanced Colored Stones (ATC), and Scientific Gemmology (SGC) courses.</p>
<p>Featured in many gem and jewelry periodicals, Jeffery has also appeared in interviews on the ABC, BBC, CCTV, CNA, CNN, NBC and GEO. He has been quoted in Time, USA Today, National Geographic, Discover, GIA’s Gems &amp; Gemology, Gem-A’s Journal of Gemmology, ICA’s InColor, Rivista Italiana di Gemmologia/Italian Gemological Review and many other publications around the world. A guest speaker at seven GIA Gem Gatherings as well as many gemological conferences &amp; universities, Jeffery is also an Honorary Professor for the <a href="https://www.aigsthailand.com" target="_blank" rel="external noopener" data-wpel-link="external">AIGS – Asian Institute of Gemological Sciences</a> in Bangkok, Thailand.</p>


Jeffery Bergman, SSEF SGC

<p>Dr. Joel E. Arem has more than 60 years of experience in the world of gems and minerals. After obtaining his Ph.D. in Mineralogy from Harvard University, he has published numerous books that are still among the most widely used references and guidebooks on crystals, gems and minerals in the world.</p>
<p>Co-founder and President of numerous organizations, Dr. Arem has enjoyed a lifelong career in mineralogy and gemology. He has been a Smithsonian scientist and Curator, a consultant to many well-known companies and institutions, and a prolific author and speaker. Although his main activities have been as a gem cutter and dealer, his focus has always been education.</p>


Joel E. Arem, Ph.D., FGA

<p>Fatma Oya Borahan, GG, FGG has Graduate Gemologist and Diamond Diplomas from the Gemological Institute of America (GIA) the German Gemmological Association (DGemG) and Gemmological Association of Great Britain (GemA). <a href="http://birdamlasu.com/">birdamlasu.com</a></p>


Fatma Oya Borahan, GG, FGG

<p>Barbara Smigel is a GIA certified gemologist, facetor, jewelry designer, gem dealer, gemology instructor and creator of the well-regarded educational websites <a href="http://www.acstones.com">acstones.com</a> and <a href="http://www.bwsmigel.info">bwsmigel.info</a>.</p>


Barbara Smigel, PhD. GG

<p>A geologist, environmental engineer and Caltech graduate, Addison's interest in the mesmerizing and beautiful results of earth's geological processes began in her elementary school's environmental club. When she isn't writing about gems and minerals, Addison spends winters studying ancient climates in Iceland and summers hiking the Colorado Rockies.</p>


Addison Rice

<p>Dr. Gerald Wykoff is GG (Graduate Gemologist), a CSM (Certified Supreme Master gemcutter), educator, and author of several gemology books. He founded the American Society of Gemcutters in the 1980s and served for more than 10 years as the editor of its monthly magazine, American Gemcutter.</p>


Dr. Gerald Wykoff GG CSM

<p>The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as <a href="https://rockpeddler.com/product-category/instructional-materials/"><em>Gram Faceting Designs</em></a>.</p>


Jeff R. Graham

<p>A gem lover and writer, Phoebe holds a graduate gemologist degree from the Gemological Institute of America and masters in writing from Columbia University. She got her start in gemology translating and editing <em>Colored Stone and Mineral Highlights</em> for a professor based in Shanghai. Whether in LA, Taipei, or New York, Phoebe spends her time searching for gems to design and being lost in good books.</p>


Phoebe Shang, GG

<p>Kyrylo Gubariev, Graduate Gemologist (GG, AJP) is a gemologist with a passion for sharing his knowledge with fellow gem lovers. Originally from Ukraine, he is currently based in Bangkok, Thailand.</p>


Gemstone	Corundum, Sapphire
Treatments	Oiling
Natural or man made	Natural
Origin details	Rock Creek, Montana, U.S.A. (this is the origin)
Carat Weight	12
Height	34
Width	56
Depth	78
Gem State	Faceted
Faceter	Daniel Stair (faceter name)
Clarity	F
Transparency	Transparent
Photo phenomena	Play of Color
Luster	Silky
Polish	Dull
Fracture	Silky
Dispersion	Moderate
Luminescence	UV-Short
Photo pleochroism	Trichroic (3 colors)
Flaws	Cavity (pit)
Lighting	Natural
Inclusions	Dendritic
Crystal System	Tetragonal