Gems & Gemology Summer 2021, Vol. 57, No. 2

Summer 2021 G&G Publication Information

Editorial Staff

Duncan Pay
Editors, Lab Notes 
Thomas M. Moses
Shane F. McClure
Contributing Editors 
James E. Shigley
Raquel Alonso-Perez
Managing Editor 
Stuart D. Overlin
Editors, Micro-World 
Nathan Renfro
Elise A. Skalwold
John I. Koivula
Editor-in-Chief Emeritus
Alice S. Keller
Associate Editor
Brooke Goedert
Editors, Gem News 
Emmanuel Fritsch
Gagan Choudhary
Christopher M. Breeding
Customer Service
Martha Erickson
(760) 603-4502
Technical Editors
Tao Hsu
Jennifer Stone-Sundberg
Assistant Editor
Erin Hogarth

Production Staff

Creative Director
Faizah Bhatti
Robert Weldon
Russel Samson
Multimedia Designer
Michael Creighton
Multimedia Associate
Christopher Bonine
Photo/Video Producer
Kevin Schumacher
Video Production
Larry Lavitt
Pedro Padua
Albert Salvato

Editorial Review Board

Ahmadjan Abduriyim
Tokyo, Japan
Jaroslav Hyršl
Prague, Czech Republic
Sudarat Saeseaw
Bangkok, Thailand
Timothy Adams
San Diego, California
Dorrit Jacob
Canberra, Australia​
Karl Schmetzer
Petershausen, Germany
Edward W. Boehm
Chattanooga, Tennessee
A.J.A. (Bram) Janse
Perth, Australia
Andy Shen
Wuhan, China
James E. Butler
Washington, DC
Mary L. Johnson
San Diego, California
Guanghai Shi
Beijing, China
Alan T. Collins
London, UK
Stefanos Karampelas
Paris, France​
James E. Shigley
Carlsbad, California
Sally Eaton-Magaña
Carlsbad, California
Lore Kiefert
Lucerne, Switzerland
Elisabeth Strack
Hamburg, Germany
John L. Emmett
Brush Prairie, Washington
Simon Lawson
Maidenhead, UK
Nicholas Sturman
Bangkok, Thailand
Emmanuel Fritsch
Nantes, France
Ren Lu
Wuhan, China
D. Brian Thompson
Florence, Alabama
Eloïse Gaillou
Paris, France
Thomas M. Moses
New York, New York
Fanus Viljoen
Johannesburg, South Africa
Al Gilbertson
Carlsbad, California
Laura Otter
Canberra, Australia
Wuyi Wang
New York, New York
Gaston Giuliani
Nancy, France
Aaron Palke
Carlsbad, California​
Christopher M. Welbourn
Reading, UK
Lee A. Groat
Vancouver, Canada
Ilene Reinitz
Chicago, Illinois
Chunhui Zhou
New York, New York
Yunbin Guan
Pasadena, California
Nathan Renfro
Carlsbad, California
J.C. (Hanco) Zwaan
Leiden, The Netherlands​
Peter Heaney
University Park, Pennsylvania
Benjamin Rondeau
Nantes, France
Richard W. Hughes
Bangkok, Thailand
George R. Rossman
Pasadena, California

About the Cover

John McDevitt King’s mixed-media painting “Overblue” illustrates how gems and fine art are intertwined. The artist acknowledges the subtle effects of fluorescence on diamond appearance—usually none. But when fluorescence is strong, it may soften the light/dark contrast with a unique glow. The proportions of the sketched diamonds relate to the reported occurrence of fluorescence strength, starting with the most common (None to Faint) and receding to Medium to Strong, all the way to the scarcely encountered Very Strong. King, a longtime senior leader of GIA’s laboratory, is an author of G&G’s Winter 1997 fluorescence article and many others.

Printing is by L+L Printers, Carlsbad, CA.

GIA World Headquarters The Robert Mouawad Campus 5345 Armada Drive Carlsbad, CA 92008 USA

© 2021 Gemological Institute of America All rights reserved. ISSN 0016-626X


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Database Coverage

Gems & Gemology’s impact factor is 1.775, according to the 2020 Thomson Reuters Journal Citation Reports (issued July 2021). G&G is abstracted in Thomson Reuters prod­ucts (Current Contents: Physical, Chemical & Earth Sci­ences and Science Citation Index–Expanded, including the Web of Knowledge) and other databases:

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Manuscript Submissions

Gems & Gemology, a peer-reviewed journal, welcomes the submission of articles on all aspects of the field. Please see the Author Guidelines at or contact the Managing Editor. Letters on articles published in G&G are also welcome. Please note that Field Reports, Lab Notes, Gem News International, Micro-World, and Charts, and Diamonds from the Deep are not peer-reviewed sections but do undergo technical and editorial review.

Copyright and Reprint Permission

Abstracting is permitted with credit to the source. Libraries are permitted to photocopy beyond the limits of U.S. copy­right law for private use of patrons. Instructors are permitted to reproduce isolated articles and photographs/images owned by G&G for noncommercial classroom use without fee. Use of photographs/images under copyright by external parties is prohibited without the express permission of the photographer or owner of the image, as listed in the credits. For other copying, reprint, or republication permission, please contact the Managing Editor.

Gems & Gemology is published quarterly by the Gemologi­cal Institute of America, a nonprofit educational organization for the gem and jewelry industry.

Any opinions expressed in signed articles are understood to be opinions of the authors and not of the publisher.