GIA Spring G&G: Color and Serenity Coated Diamonds

From GIA, Carlsbad, Calif. - The Spring 2007 edition of Gems & Gemology features articles on pink-to-red coral, a new type of coated diamond, and trapiche tourmaline from Zambia, plus the annual G&G Challenge quiz and more.

Leading the Spring issue is “Pink-to-Red Coral: A Guide to Determining Origin of Color,” by Christopher Smith and co-authors. Pink-to-red coral has been a popular ornamental gem material for thousands of years, and pale coral is often dyed to give it this desirable color. The article compares the identifying characteristics of natural and dyed pink-to-red coral and reports, based on the study of more than a thousand samples, that while magnification and exposure to acetone will identify the presence of dye in many cases, Raman spectroscopy can always establish conclusively (and nondestructively) whether the color is natural or dyed.

“The supply of natural-color pink-to-red coral has diminished in recent years, which means we’ll see more of the dyed material,” said G&G editor-in-chief Alice Keller. “This article is an essential tool in determining if the color is natural or artificial.”

The next feature is “Serenity Coated Colored Diamonds: Detection and Durability,” by Dr. Andy Shen and colleagues. A new multi-film coating technique from Serenity Technologies produces a variety of evenly distributed, natural-looking “fancy” colors on diamonds, including intense blue, green, yellow, and orange to pink to purple-pink. The authors found that while this sophisticated coating can be detected by careful examination with a microscope, UV-Vis absorption spectra and chemical analysis will confirm the treatment. Their study also revealed that the coating is stable to some standard repair and cleaning procedures but may be damaged by others.

Rounding out the Spring issue lineup is “Trapiche Tourmaline from Zambia.” Thomas Hainschwang and coauthors examine these unusual green tourmalines that display a striking six-rayed growth pattern in cut slices, reminiscent of trapiche emerald or ruby. The find in northwestern Zambia is believed to be the first occurrence of true trapiche tourmaline.

The journal’s regular Lab Notes section reports on the latest discoveries at the GIA Laboratory, while the Gem News International section contains highlights from this year’s Tucson gem and mineral shows, as well as other gemological happenings from around the world.

This issue also marks the twentieth anniversary of the G&G Challenge, the annual quiz that lets readers test their gemological knowledge. The 25 multiple-choice questions are based on G&G feature articles from 2006. Successful participants will receive a GIA Continuing Education Certificate and, if they score one hundred percent, recognition in an upcoming issue of Gems & Gemology.

To order the Spring 2007 issue or to subscribe, visit www.gia.edu/gemsandgemology or contact Circulation Coordinator Debbie Ortiz at dortiz@gia.edu. Call toll-free 800-421-7250, ext. 7142. Outside the U.S.and Canada, call 760-603-4000, ext. 7142.

About GIA

An independent nonprofit organization, the Gemological Institute of America (GIA) is recognized as the world's foremost authority in gemology. Established in 1931, GIA has translated its expert knowledge into the most respected gemological education available. In 1953, the Institute created the International Diamond Grading System™ which, today, is recognized by virtually every professional jeweler in the world. Through research, education, gemological laboratory services, and instrument development, the Institute is dedicated to ensuring the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science, and professionalism. GIA’s website address is http://www.gia.edu/. Media queries contact: Laura Simanton, 760-603-4112.