Pale colors and attractive button shapes are typical of quahog pearls. © Kojima Pearl. Used with permission.

Calcareous Concretions - Natural, Rough, Pink - International Gem Society

Home

Gem Gallery

Calcareous Concretions – Natural, Rough, Pink

Join 10,000+ members helping each other learn. For gemologists, gem collectors, hobbyists, jewelers, lapidaries and everyone in between.

International Gem Society

https://www.gemsociety.org/wp-content/uploads/2015/06/igs_newsletter_logo.png

International Gem Society LLC

Calcareous Concretions

Pale colors and attractive button shapes are typical of quahog <a href="https://www.gemsociety.org/article/pearl-jewelry-and-gemstone-information/" data-wpel-link="internal">pearls</a>. © <a href="https://kojimapearl.com/" data-wpel-link="external" target="_blank" rel="external noopener nofollow">Kojima Pearl</a>. Used with permission.

Quahog Pearl Buying Guide

Appraisals

Gem Cutting

Gemological Laboratories

Gemstones

Rough Gems and Mineral Specimens

Jewelry

Gemology Supplies and Equipment

Auctions

Gem Treating

Informational Resources

Lapidary Supplies and Equipment

Special Services

Ruby Buying Guide

Emerald Buying Guide

Sapphire Buying Guide

Aquamarine Buying Guide

An Introduction to Gem Identification

Destructive Gemstone Testing

Enhanced Gem Inclusions

Identifying Synthetic Diamonds

Celebrity Engagement Rings

Ruby and Sapphire Grading Tools

Cerussite Value, Price, and Jewelry Information

Ouro Verde Quartz: History and Treatment

Tanzanian Corundum

Is This a Topazolite Garnet?

Nigerian Gemstones

Is This an Opal?

Gem Enthusiast Monthly Gift

Gem Enthusiast Annual Gift

For Professionals and Dedicated Enthusiasts

Professional Monthly Gift

Professional Annual Gift

Free Professional Business ListingGet your company in front of 12,000 gem enthusiasts and professionals.

Gemstone Buying GuidesAdvice that you can trust written by industry experts, without the giant price tag.

Professional Certification ProgramsOnly IGS Professional members are eligible to enroll in Professional Certification Programs

Advanced Filters in our Gem GalleryFilter images based on Gem State, Shape, Color, and Natural or Lab-Made

Gem Identification GuidesBe confident in what you have and avoid the heartbreak and cost of identification mistakes.

50% off all Mini CoursesOver $300 in savings

In-Depth Premium ArticlesIncluding 20 years of back catalog

Gem Price Guide (accurate and up-to-date)Reliable pricing data can cost hundreds through other sources. It’s included with IGS.

Gem Enthusiast

Gem Enthusiast Annual

Gem Enthusiast Monthly

Professional Certification ProgramsOnly IGS Professional members are eligible to enroll in Professional Certification Programs (additional $400 per certification course)

More Advanced Filters in our Gem GalleryFilter images based on all of the basic filters PLUS Transparency, Multi-Color, Pleochroism, Phenomena, Treatment, and Inclusions

Access to All Mini Courses$600 value included in your membership

Professional

Professional Annual

Professional Monthly

Birthstone Chart

37 Blue Gemstones (Names, Pics, & More)

Gemstone Hardness and Wearability

10 Rare Engagement Ring Stones that Won’t Break the Bank

Evolution of the Pigeon’s Blood Ruby Color Grade

How Old Is My Zircon?

Appraising Turquoise: Challenges for Gemologists

Turquoise Treatments and Synthetics Guide

In 2012, Donald Clark retired and passed along stewardship of the IGS to the Rosen family, who were longtime members of IGS. Lisa Rosen runs the day-to-day operation of IGS and  <a href="https://www.ganoksin.com/">The Ganoksin Project, a technical resource website for bench jewelers and jewelry manufacturers</a>.  Lisa strongly believes that IGS must remain a cost-effective, accurate, and comprehensive resource for all those interested in gemology. IGS is our passion, and it is a family business.

Lisa Rosen

The late 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 &#8220;Modern Faceting, the Easy Way.&#8221;

Donald Clark, CSM IMG

Jeffery Bergman, SSEF SGC, founder and director of <a href="http://www.primagem.com/">8th Dimension Gems</a> in Thailand, is an American gem dealer with more than 40 years of experience in gemstone and fine jewelry mining, cutting, wholesaling and retailing. His career has taken him to more than 50 countries and every continent except Antarctica. He has appeared on the BBC, CNN, NBC, ABC and GEO; and has been featured in Time, USA Today, National Geographic, Gems &amp; Gemology and Discovery Channel magazine. He is a regular guest speaker at gem lab seminars and gemological association conferences and universities.

Jeffery Bergman, SSEF SGC

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.
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. <a href="https://www.joelarem.com/">joelarem.com</a>

Joel E. Arem, Ph.D., FGA

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>

Fatma Oya Borahan, GG, FGG

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>.

Barbara Smigel, PhD. GG

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.

Dr. Gerald Wykoff GG CSM

A geologist, environmental engineer and Caltech graduate, Addison&#8217;s interest in the mesmerizing and beautiful results of earth&#8217;s geological processes began in her elementary school&#8217;s environmental club. When she isn&#8217;t writing about gems and minerals, Addison spends winters studying ancient climates in Iceland and summers hiking the Colorado Rockies.

Addison Rice

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/">Gram Faceting Designs</a>.

Jeff R. Graham

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.

Kyrylo Gubariev, Graduate Gemologist (GG, AJP)

Jim Buday was born and raised in Wisconsin. He attended college for biology, but realized that he preferred to work with his hands. He became a general contractor and home flipper. Jim then taught himself to cut gems by watching instructional YouTube videos and reading online forums. By 2019, he was confident enough in his skills to pursue selling his work. He founded the Reddit thread, Shinypreciousgems, which now sits at more than 25,000 members. Jim now works with gems and jewelry full time, and has also partnered with several jewelers to offer settings to his gemstone clients. Recently, Jim started creating his own gem designs. In his free time, Jim enjoys the outdoors, working on his land, and is building a house with his girlfriend, Raeanna.

Gemstone	Calcareous Concretions
Natural or man made	Natural
Gem State	Rough
Color	Pink
Transparency	Opaque