Editors

A Hands-on Lesson in Telling Gemstones Apart

EditorsApr 18, 2016

A Hands-on Lesson in Telling Gemstones Apart

Senior Editor Brecken Branstrator recounts what she learned at an AGS Conclave education session on identifying gemstones presented by Gem-A.

20160418_GemA-Article.jpg

The American Gem Society knocks it out of the park every year for their Conclave event. The keynote speakers are top-notch, and the education sessions cover a wide variety of topics presented by experts in the industry.

Held in Washington, D.C. this year, Conclave again was full of great sessions, from a panel on bridal trends, to updates on diamond prices and grading reports, to a fascinating session on diamonds and their healing powers.

A particularly cool one that I got to attend was held Friday by The Gemmological Association of Great Britain (Gem-A).

In “Separating Similar-Looking Stones,” Gem-A’s Claire Mitchell began by walking session attendees through the steps used to identify a stone, starting with observation and then working through the instruments that can help jewelers tell apart similar-looking stones.

I loved this session because it was a hands-on experience--half the session was a presentation and the other half had us using the instruments ourselves. (I think a lot of people were excited about this session, as it had a waiting list and attendees were lined up before it started. I was lucky enough to just make it in and get a seat with equipment.)

First, Mitchell walked us through what kind of observations can be made before using any instruments.

For example, inclusions such bubbles and swirls or molding marks that indicate a paste glass might tell you that a gemstone is man-made.

Inclusions in natural stones can help indicate what the stone might be as well, such as “horsetail inclusions” found in demantoid garnets or “lily pads” that show up in peridot.

Next, Mitchell walked us through the use of instruments such as a polariscope, spectroscope and a dichroscope.

We got to use all three on gemstone samples provided so we could see for ourselves how each worked and what the stones looked like through the instruments.

The polariscope, for example, can tell you if a stone has double or single refraction, while a spectroscope is a diagnostic tool showing a spectrum of colors that is “like having a bar code for a gemstone” to help with identification.

My personal favorite was the Chelsea Color Filter, which is a dichromatic filter that transmits two wavelengths only to help identify certain green, red and blue stones, as well as detecting dyes in certain gems.

Above is a picture of three different blue stones--aquamarine, topaz and spinel--under the filter.

I
love any opportunity that allows me the chance to learn more about stones, and the sentiment in the room seemed to indicate that everyone else found the session as useful as I did.

While I’m always trying to see if I can guess what a gemstone is when I see it, Gem-A stressed that there should always be more tests involved to figure out a stone’s true identity. This session definitely made me want to go out and get some of these instruments for myself.
Brecken Branstratoris the senior editor, gemstones at National Jeweler, covering sourcing, pricing and other developments in the colored stone sector.

The Latest

Black and white photo of Tony Bennett near a microphone
WatchesAug 07, 2025
Bulova’s New Collection Honors Tony Bennett

The first watch in the series commemorates his participation in the Civil Rights movement, marching from Selma to Montgomery in 1965.

Sapphire page in Chatham’s “Ultimate Lab-Grown Catalog”
Lab-GrownAug 07, 2025
Chatham Releases Catalog for Loose Lab-Grown Gemstones

The catalog contains a complete listing of all the loose gemstones in stock, as well as information about the properties of each stone.

Rembrandt Blue Jay, Hummingbird, Cardinal Bird Charms
TechnologyAug 07, 2025
Rembrandt Charms Debuts New Website, Bird Charms

The company added a retailer dashboard to its site and three new birds to its charm collection, the cardinal, blue jay, and hummingbird.

rio-article photo-diamond.jpg
Brought to you by
Taking the Moment Head On: How Rio Grande Champions the Present & Future of Fine Jewelry

As a leading global jewelry supplier, Rio Grande is rapidly expanding and developing new solutions to meet the needs of jewelers worldwide.

Shipping containers on a ship
Policies & IssuesAug 06, 2025
Tariff on India to Rise to 50%, Trump Says

An additional 25 percent tariff has been added to the previously announced 25 percent.

Weekly QuizJul 31, 2025
This Week’s Quiz
Test your jewelry news knowledge by answering these questions.
Take the Quiz
Claire’s storefront
MajorsAug 06, 2025
Claire’s Files for Chapter 11 Bankruptcy Again

The jewelry and accessories retailer plans to close 18 stores as part of the proceedings.

Smith & Son Jewelers storefront Springfield Massachusetts
IndependentsAug 06, 2025
Smith & Son Jewelers to Close 107-Year-Old Location

Its Springfield, Massachusetts, store is set to close as owner Andrew Smith heads into retirement.

an instructor and a student in a bench jewelry classroom
Brought to you by
Investing in the Next Generation of Bench Jewelers

The Seymour & Evelyn Holtzman Bench Scholarship from Jewelers of America returns for a second year.

Zahn-Z Beluga Spout Grey Spinel Ring and Beluga Spout Mandarin Garnet Ring
CollectionsAug 06, 2025
Zahn-Z Swims With Whales in ‘Beluga’ Collection

Designer Hiba Husayni looked to the whale’s melon shaped-head, blowhole, and fluke for her new chunky gold offerings.

Paola De Luca presenting Trendbook 2026+ at Vicenzaoro
TrendsAug 06, 2025
Paola De Luca to Release Trendbook 2027+

She will present the 23rd edition of the trend forecasting book at Vicenzaoro on Sept. 7.

Omar Roy mugshot
CrimeAug 05, 2025
Report: Suspect Arrested in 1992 Murder of Miami Jeweler

Omar Roy, 72, was arrested in connection with the murder of jeweler Dionisio Carlos Valladares.

Mignon Faget Beyond Katrina Pendant and Beyond Katrina Pin
CollectionsAug 05, 2025
Mignon Faget Commemorates 20th Anniversary of Hurricane Katrina

The New Orleans-based brand’s “Beyond Katrina” jewels honor the communities affected by the storm.

National Jeweler columnist Lilian Raji
ColumnistsAug 05, 2025
The PR Adviser: Affiliate Marketing Is the Cost of Coverage

Lilian Raji explains why joining an affiliate network is essential for brands seeking placements in U.S. consumer publications.

Jewelers of America Logo
Events & AwardsAug 05, 2025
JA Announces Seymour & Evelyn Holtzman Bench Scholarship Winners

The organization has awarded a total of $42,000 through its scholarship programs this year.

2026 Gem Awards logo
Events & AwardsAug 04, 2025
Gem Awards, David Yurman Introduce $50K Grant for Emerging Designers

The winner of the inaugural David Yurman Gem Awards Grant will be announced live at the 2026 Gem Awards gala.

Marlo Laz peridot and diamond Alexandra earrings
TrendsAug 04, 2025
Amanda’s Style File: August’s Bright Baubles

As summer winds down, celebrate the sunny disposition of the month’s birthstones: peridot and spinel.

Surveillance image of Watch King robbery suspect
CrimeAug 04, 2025
‘The Watch King’ Assaulted, Robbed in Queens

Moshe Haimoff, a social media personality and 47th Street retailer, was robbed of $559,000 worth of jewelry by men in construction outfits.

Xavier Dibbrell
MajorsAug 04, 2025
Borsheims Welcomes New Assistant Facilities Manager

Xavier Dibbrell brings more than a decade of experience to the role.

Signet Jewelers logo
MajorsAug 01, 2025
Helzberg President Julie Yoakum Moves Over to Signet Jewelers

The addition of Yoakum, who will lead Kay and Peoples, was one of three executive appointments Signet announced Thursday.

Mike Alexander
MajorsAug 01, 2025
Jewelers Mutual Names Mike Alexander as President

The insurance company’s previous president and CEO, Scott Murphy, has split his role and will continue as CEO.

 Gemfields rough rubies
SourcingAug 01, 2025
Gemfields’ Auction Revenue Drops 50% in H1

The nearly six-month pause of operations at its Kagem emerald mine earlier this year impacted the miner’s first-half results.

Hernsdorf Tears of Aphrodite Necklace
CollectionsAug 01, 2025
Piece of the Week: Hernsdorf’s ‘Tears of Aphrodite’ Necklace

The necklace uses spinel drops to immortalize the moment Aphrodite’s tears mixed with her lover Adonis’ blood after he was fatally wounded.

Stock image of a polished diamonds being held by tweezers
SourcingJul 31, 2025
De Beers Records $189M First-Half Loss

The diamond miner and marketer warned last week that it expected to be in the red after significantly cutting prices in Q2.

Lindsey Scoggins Studio convertible flower earrings
Events & AwardsJul 31, 2025
These Are the 2025 CASE Award Winners

Jewelers of America’s 35th annual design contest recognized creativity, artistry, style, and excellence.

Matthew Tratner, new president of Continental Buying Group
IndependentsJul 31, 2025
Matthew Tratner Takes Over as CBG President

Tratner succeeds Andie Weinman, who will begin stepping back from the buying group’s day-to-day operations.

Stock image of rough diamonds from the Kimberley mine
Policies & IssuesJul 30, 2025
Tariff on India Will Be 25%, Trump Says

The president made the announcement via Truth Social Wednesday, adding that India also will face a penalty for its dealings with Russia.

Pomellato Mini London blue topaz and diamond bracelet
FinancialsJul 30, 2025
Kering's Jewelry Brands Resilient As H1 Sales Slide 16%

The luxury titan’s star brand Gucci continued to struggle amid a "tough" environment.

×

This site uses cookies to give you the best online experience. By continuing to use & browse this site, we assume you agree to our Privacy Policy