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Gem-A

Creating and supporting gemmologists since 1908.
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02/06/2026

A close-up view of doubling in titanite sphene 🔎

In gemmology, 'doubling' refers to the visible duplication of facet edges or internal features when you look through a stone. It is one of this gemstone's most distinctive optical characteristics.

The reason titanite shows this so strongly is its extremely high birefringence (double refraction). When light enters the crystal, it splits into two rays travelling at different speeds and along different paths. Your eye can sometimes see both images simultaneously, making facet junctions appear doubled or slightly fuzzy.

Many doubly refractive gems show some doubling, but sphene's birefringence is among the highest of any commonly faceted gemstone. As a result, the effect is often visible even to the naked eye. Gemmologists frequently use this as a diagnostic feature when identifying the stone.

Get to grips with more gemmological principles by studying the Gem-A Gemmology Foundation – your only pathway towards FGA status.

Find out more here: https://gem-a.com/gemmology-courses/

📸 Gabriel Kleinberg

01/06/2026

The Gem-A journey starts here 🎓

Explore your passion for gemmology with our globally recognised Gemmology Foundation course – your only pathway to achieving the coveted FGA membership designation.

We are currently accepting applications for courses starting in September, including our daytime and evening classes at Gem-A London and our popular online learning route.

Secure a Gem-A Level 4 Certificate in Gemmology and equip yourself with robust, scientific knowledge of gemstones that will support your career ambitions.

✅ No previous qualifications required
✅ Fully illustrated course notes
✅ Portable instrument kit supplied
✅ Stone set with 20 rough and cut gems supplied
✅ Gem-A Membership for the duration of your studies

Find out more and apply here: https://gem-a.com/gemmology-courses/

Email [email protected] to find out more and get your questions answered.

27/05/2026

You've got your FGA post-nominals… now add EG to your title 👏

Our FEEG Preparation Workshop is ideal for Gem-A Diploma graduates who want to enhance their knowledge, test their skills and secure another internationally recognised qualification.

Join us at Gem-A London for three days of learning, starting on June 29.

You will have the option to take the FEEG examination on Thursday, July 2, although this is not mandatory.

⚠️ IMPORTANT: The FEEG exam requires separate registration and payment by June 2. We will not be able to take any further bookings for the FEEG exam after this time. Bookings after this date will be for the workshop only.

Make sure to read your Diploma theory notes before attending!

Last chance to secure your place here: https://gem-a.com/event/feeg-preparation/

Get your questions answered by emailing [email protected].

📸 Gemstone under the microscope with a fibre optic light source by Gabriel Kleinberg.

26/05/2026

Are you ready to secure a globally recognised, industry-renowned qualification? 🎓

Join our next cohort of Gemmology Foundation students starting in September 2026.

You can choose to study in person at Gem-A London or online to achieve your goals, learn new skills, and enhance your career opportunities.

Plus, Membership of Gem-A is included for all students for the duration of your course, enabling you to benefit from extra resources, events, and our esteemed publications.

💻 Dedicate four months to securing your Gem-A Level 4 Certificate in Gemmology. Find out more and explore your options here: https://gem-a.com/gemmology-courses/

Remember, our Education team is here to help. Email [email protected] to ask questions and find out what Gem-A pathway is right for you.

📸 Covellite inclusions in quartz at 10x magnification by Gabriel Kleinberg.

25/05/2026

The Spring 2026 edition of Gems&Jewellery magazine is now available for Gem-A Members to read online 📚

In this issue, we take a closer look at the biggest trends to emerge from the Tucson gem shows, discover more about Birmingham’s Jewellery Quarter, and ask whether 2026 will bring about a rebound in the diamond market.

Elsewhere, we spotlight the heritage crafts at risk of total extinction, interview esteemed analytical microscopist John I. Koivula FGA, and review a new book dedicated to the work of Solange Azagury-Partridge.

Gem-A Members can read the issue here: https://gem-a.com/publications/gems-and-jewellery/spring-2026-volume-35-issue-1/

📸 On the cover: Platinum rings created by Mary van der Aa, with centre stones cut by Todd Wacks (Tucson Todd's Gems). The Cosmic Candy ring uses a 4.34 ct Mahenge spinel, while the Aurora Hex ring features a 4.72 ct bicolour pink-and-yellow tanzanite (zoisite). Photo by Robert Weldon, courtesy of Mary van der Aa Iconic Jewels.

Become a Gem-A Member to access our magazines: https://gem-a.com/membership/

21/05/2026

Don't miss the first event being hosted by the newly reinstated Gem-A North West Branch, taking place on June 23 in Liverpool 🎉

Bespoke jewellery designer Katrina Young will lead a session titled 'The Depths of Jewellery Design', focusing on her career journey, as well as her perceptions of skills shortages in the UK. Katrina will offer a behind-the-scenes look at the tools, training and client conversations that bring dream jewellery creations to life.

This great event is open to all, including Gem-A Members, non-members and students. More information can be found here: https://gem-a.com/event/the-depths-of-jewellery-design/

The Gem-A North West Branch is a hub for gemmologists and jewellery professionals based in Cheshire, Cumbria, Greater Manchester, Lancashire and Merseyside. Find out how you can become a volunteer by contacting Kay Oakes at [email protected].

📍 Find your nearest Gem-A Branch and contact the organisers, here: https://gem-a.com/membership/branches/

20/05/2026

Gem-A was proud to be a Silver Sponsor of this year’s Valuers’ Conference, hosted by the Institute of Registered Valuers.

Our CEO, Cath Hill, travelled to Birmingham over the weekend of May 16-17 to meet Gem-A Members, engage with industry peers, and catch up with plenty of friends in the trade.

Here, she is pictured with lapidarist Justin Prim, who is the author of The Historic Teachings of Gemcutting, which is available via Gem-A Instruments: https://shop.gem-a.com/product/bks0420-the-historic-teachings-of-gemcutting-by-justin-prim/

Cath also met with Sarah Steele, a former Gem-A Conference speaker and renowned expert on Whitby Jet.

Also pictured here is Mark Cullinan, the great-grandson of Sir Thomas Cullinan, the discoverer of the Cullinan Diamond. Cath is holding a replica of the original rough, which was cut into nine major gems and many others; the two largest are set in the British Crown Jewels.

A huge thank you to the National Association of Jewellers, the Institute of Registered Valuers and Headline Sponsor Bonhams for hosting such a worthwhile event.

19/05/2026

An exclusive event for Gem-A Members and Students… 💫

Join us at Gem-A HQ in London for a unique hands-on gemstone experience, led by Sam and Charles Bexfield of Charles Bexfield Ltd.

🔜 June 13, 10 AM - 2 PM

This is an unrivalled opportunity to discover the many exceptional gemstones in the Gem-A collection and examine some extra special specimens with your own instruments or our professional equipment.

Sam and Charlie will offer expert guidance, share their own insights, and showcase samples from their own stock, with selected pieces available to purchase on the day.

Find out more and secure your place here: https://gem-a.com/event/inside-the-vault-a-hands-on-gemstone-experience/

Become a part of the Gem-A community to start receiving our magazines, secure exclusive discounts and gain access to special events: https://gem-a.com/membership/

18/05/2026

Our Diamond Grading & Identification Lab Class is just around the corner 💎

Join us at Gem-A London for five days, starting on July 6, to learn more about handling rough and polished diamonds, grading techniques, synthetic and simulant identification methods, and so much more.

No prior diamond experience is necessary. Instead, we look for individuals who are passionate about diamonds and want to improve their practical skills.

Upon completion, you will receive a Gem-A Diamond Practical Certificate, which is a great addition to your professional CV.
Can’t make it in July? You can also apply to join our next cohort in October 2026.

Discover more via the Gem-A website here: https://gem-a.com/education/study-diamonds/diamond-grading-identification-lab-class/

If you have questions, send us an email at [email protected].

📸 Photographs by Henry Mesa at Gem-A.

14/05/2026

CVD-grown diamond with multiple layering under deep UV 💎

Recently, the Stuller Gemological Laboratory tested a 0.45 ct round brilliant, near-colourless CVD-grown synthetic diamond. Upon careful inspection with an in-house deep-UV imaging instrument, the sample exhibited green luminescence and displayed an unusual abundance of growth layers.

A total of 51 parallel, straight layers showing slightly brighter yellowish luminescence were identified, spanning the entire body of the gem, spaced at consistent 73 µm intervals. This likely results from an automatic recurring doping process.

📸 Viewed with deep-UV radiation, a 0.45 ct near colourless CVD-grown diamond exhibits green luminescence with some linear growth layers. The thicker, brighter line is likely a typical start-stop layer. Photo by S. O'Neal.

📚 Gem-A Members can read more in The Journal of Gemmology (Volume 40, No. 1, 2026): https://gem-a.com/publications/the-journal-of-gemmology/volume-40-issue-1-2026/

Become a Gem-A Member to start receiving our publications: https://gem-a.com/membership/

Address

21 Ely Place
London
EC1N6TD

Opening Hours

Monday	9am - 5pm
Tuesday	9am - 5pm
Wednesday	9am - 5pm
Thursday	9am - 5pm
Friday	9am - 5pm

Telephone

+442074043334

Website

http://www.gem-a.com/

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