Creating and supporting gemmologists since 1908.

Operating as usual


Something special from southeastern Finland 🤩

Here, we can see an uncommon type of labradorite feldspar known as spectrolite.

This gem exhibits a more varied range of colours than other labradorites, often in broad flashes. It is also recognised as the Finnish national gemstone!

📸 Gabriel Kleinberg.

Start your gemmology journey with the Gem-A Gemmology Foundation course, starting in August and September 2024:


Join our next cohort of students in August and September 2024 ⏰

Discover more about our upcoming Gemmology Foundation, Gemmology Diploma and Diamond Diploma courses on our website:

Remember, you can study in your own time and at your own pace with GemIntro – our beginner’s online-only course:

📸 Dumortierite in quartz, photographed by Gabriel Kleinberg.


Did you read a Gem Note about a new hot-pressing technique for amber in The Journal of Gemmology (Vol. 39, No. 1)? 📚

In recent years, a new hot-pressing technology has emerged for manufacturing amber beads. Pieces of Baltic amber are first roughly cut into the desired bead sizes, and then moulds of different diameters are used to apply heat and pressure.

Various external and internal features can help identify hot-pressed amber beads, including patchy areas showing interference colours (pictured).

📸 Photomicrograph by Yamei Wang.

Gem-A Members can log in to read the latest edition:

Photos from Gem-A's post 11/06/2024

Women of Impact (Part One) 🥳

In the Spring 2024 edition of Gems&Jewellery magazine, Jennifer-Lynn Archuleta and Olga González FGA DGA interviewed women in various gemmology-related fields about their careers.

Included among these inspiring women are:

Adrianne Sanogo, Co-Founder and Education Chair of the Black in Jewelry Coalition(; Ashrafi Chalisa of the Indian Diamond and Colorstone Association ( and The Diamond Manufacturer & Importers Association of America (; Brecken Branstrator, Editor-in-Chief of GemGuide (, and Chie Murakami, Founder of Diamonds for Peace (

Stay tuned for parts two and three to see who else was featured.

Gem-A Members can read the issue here:


The Northeast Branch of Gem-A is relaunching with the support of Bonhams 🌟

Join your fellow Gem-A Members at Bowcliffe Hall in Bramham on the evening of July 15 to network, discuss current market trends, and view highlights from Bonhams' upcoming summer jewellery auctions.

The evening will be led by Mark Houghton, chair of the NE Branch, and Bonhams jewellery specialists.

Tickets are free for Gem-A Members and £5 for non-members. All are welcome!

Secure your ticket here:


The cosmic colours of bloodshot iolite 💫

Sometimes, iolite containing metallic plate-like inclusions can be purposefully cut to give the stone a sparkly effect, known as aventurescence.

When these platelets are seen in certain hues, the gem can be sold as ‘bloodshot’ iolite.

Here, we can see an example captured in close-up by Gem-A’s Gabriel Kleinberg with shades of red, purple, lilac and deep blue.

Start your gemmology journey with our Foundation course, starting in August and September 2024:


Are you looking for a challenge this summer?

GemIntro by Gem-A is an online-only short course that provides the fundamentals of gemmology to elevate your knowledge.

🌞 11 lessons
🌞 50+ videos
🌞 Ofqual Level 2 Certificate

Start learning today for just £220 with six months’ access to our online platform.

Find out more here:

📸 Cluster of quartz crystals by Gabriel Kleinberg.


The June birthstone is the historic and lustrous pearl 🐚

Contrary to popular belief, pearls are not formed when a single grain of sand irritates an oyster’s flesh, as it would simply eject the sand.

Instead, a parasite or tiny irritant that invades the mantle causes the oyster to cover it with successive layers of nacre, or mother-of-pearl, which is a combination of calcium carbonate in the form of aragonite platelets and conchiolin.

Saltwater oysters and freshwater mussels form these natural wonders.

📸 A cross-section of a natural pearl by Pat Daly.

Read more on the Gem-A GemHub:

Photos from Gem-A's post 03/06/2024

Why is peridot sometimes described as ‘oily’? 🧐

It is not intended as a criticism; it is a term traditionally associated with the colour of this stone.

On the Gem-A GemHub, Pat Daly explains why this descriptive moniker is used and what it tells us about this vibrant green mineral.

Read more here:

📸 Lily pad and biotite inclusions in peridot, a faceted stone, and a fractured gemstone, photographed by Gabriel Kleinberg and Pat Daly.


A fantastic trapiche emerald 🌟

These gems resemble the spokes of a wheel, with a hexagonal core, a six-point radial pattern, and black shale dendrites in between. They are a sensational feat of nature, typically hailing from Colombia.

Remember, this is not a case of asterism caused by light interacting with oriented needle-like inclusions.

Learn about emeralds via GemIntro, our online-only beginner’s course:

📸 Gabriel Kleinberg.


If you are new to gemmology, you may not be wholly familiar with spinel 💡

Historically, these gems were confused with corundum, especially in red hues, which adds to the mystery and intrigue for gemmologists.

We asked Gem-A tutor Pat Daly to explore this important mineral in more detail in an article on the Gem-A GemHub.

📍 Most gem spinel is found in marbles metamorphosed at high temperatures during continental collisions, such as in East Africa, Sri Lanka, and the Himalayan region, including Burma and Vietnam. 📍

Read the full article:

📸 Images by Henry Mesa, Pat Daly, and Gabriel Kleinberg.


Not long until the Northeast Branch of Gem-A officially relaunches with the support of Bonhams!

Join fellow Gem-A Members at Bowcliffe Hall in Bramham on the evening of July 15 to discuss upcoming auctions and network with fellow gemmologists.

Tickets are free for Gem-A Members and £5 for non-members.

Find out more here:

📸 Aquamarine and diamond necklace, circa 1950, courtesy of Bonhams.


There’s so much to learn about this month’s 📚

Here, we can see a synthetic hydrothermal emerald with heat haze.

The hydrothermal growth process requires heat and pressure to mimic conditions in the earth that result in natural gems.

Start your gemmology journey with our online-only GemIntro course:

📸 Gabriel Kleinberg.


Gem-A Update ✏️

The Board of Directors and Trustees of the Gemmological Association of Great Britain (Gem-A) have announced that Alan Hart has decided to step down as chief executive officer (CEO).

For the last eight years, Alan has provided leadership and stewardship and has brought positivity to the organisation. The Board would like to take the opportunity to thank Alan for his service to the organisation and wish him every success in his future endeavours.

Gem-A CEO Alan Hart FGA comments: "It has been a privilege to have led the Gemmological Association of Great Britain over the last eight years, providing services to our membership and the wider gems and jewellery industry. I feel fortunate to have been supported by a committed staff team, the Gem-A Board of Trustees, and our international partners.

"I am immensely proud of all that we have been able to achieve, especially navigating the Association through the challenges of the last few years to where it is today – a strong, resilient, and forward-looking organisation with a flourishing future."

For further information, please contact Gem-A Board of Trustees (Council) chair Justine Carmody FGA at [email protected].

Read more here:


Take a look at this specimen of emerald crystals in pyrite 🤩

This month’s has been mined for thousands of years, stretching back to Egypt near the Red Sea around 2000 BC in what were known as Cleopatra’s emerald mines.

While Egyptian emeralds were some of the first to be mined and traded, it was the discoveries of Colombian emeralds by 16th-century Spanish conquistadors like Pizarro that brought strikingly saturated green crystals to the European market – particularly to the Spanish court and beyond.

Learn more about this commercially significant gemstone via GemIntro, our online-only beginner’s course:

📸 Gabriel Kleinberg.


We are thrilled to be hosting another fantastic one-day event on July 15 led by Branko Deljanin FGA DGA of Gemmological Research Industries Inc, Canada ⏰

Join us at Gem-A HQ in London for a day dedicated to the identification of natural, treated and synthetic colourless diamonds. You’ll spend the first half of the day identifying natural diamonds and HPHT and CVD laboratory-grown diamonds while also assessing how they react to UV light conditions.

Branko will provide hands-on access to Type Ia, IIa, IIb, and Ib diamonds to test your skills and expand your knowledge.

In the afternoon, you’ll switch to screening for treatments, including clarity and colour enhancements and post-treatments for CVD-grown colourless diamonds. There will be 80 sample stones to test using various instruments.

If you’re an intermediate to advanced-level gemmologist ready to learn, this is the workshop for you!

Book your place here:

📸 Type I natural pink diamond from Argyle shows anomalous strain.


We are recruiting for a Membership Manager to join the Gem-A team in London ⏰

In this role, you will oversee the administration and strategic development of our Membership function, ensuring exceptional service delivery and engagement.

This full-time, hybrid role based in London combines office presence with the flexibility of remote work.

We are looking for someone who can deliver highly effective membership services using various digital tools. You will be adept at communication, digital campaigns, and project management.

Discover more about this exciting opportunity here:


This month’s is the fantastic emerald 💚

Did you know? The inclusions contained in almost all natural emeralds are very useful in distinguishing them from synthetic emeralds and other green stones.

The types of inclusions in some emeralds can offer an indication of their origin, although this is certainly not a foolproof method.

📸 Mica inclusions in emerald, photographed by Gabriel Kleinberg.

More information can be found here:


Join other Gem-A Members in the Northeast of England for a special event hosted by Bonhams 🌟

The Northeast Branch of Gem-A will officially relaunch on July 15 with a fantastic networking event at Bowcliffe Hall in Bramham. The evening will be led by Mark Houghton, chair of the NE Branch, plus Bonhams jewellery specialists.

Tickets are free for Gem-A Members and £5 for non-members.

Secure your place here:

📸 Art Deco 7.12-carat sugarloaf sapphire and diamond ring, circa 1920, courtesy of Bonhams.

Photos from Gem-A's post 13/05/2024

Since 2020, gem cutter Victor Tuzlukov has created faceted gemstone eggs reminiscent of, and in homage to, the work of Russian jeweller Carl Fabergé 🌟

Some fantastic examples of his work can be found in the latest edition of Gems&Jewellery magazine.

Here, we can see pieces in his collection, including the Gothic Rhapsody (top left) – an 817-carat citrine with more than 3,000 facets inspired by the stained glass of Paris’ Notre Dame Cathedral (photo Sergey No).

📸 Further photos by Laszlo Kupi, Victor Tuzlukov and Dmitry Stolyarevich.

Gem-A Members can read the issue here:


⭐️ Could the next step in your career be at Gem-A? ⭐️

We are recruiting a Systems Manager to join our team in London.

If you have experience working in an IT role, especially for an educational organisation, we would love to hear from you. The Systems Manager will be responsible for our digital platforms, including the learning management system used by our international network of students and tutors.

You would also be the first point of contact with the external teams for the main Gem-A website and CRM database.

Read the job specifications here:


Why does the study of gemmology matter? 📚

That’s the question we asked Gem-A tutor Pat Daly to answer for our latest blog post on the Gem-A GemHub.

You can read it here:

We’d love to hear your opinion, too! Why does the study of gemmology matter to you, both personally and professionally?

Share your thoughts below…

📸 A set of natural ruby samples in the Gem-A Archives.


The latest issue of Gems&Jewellery magazine contains this photograph of 'The Rose' 🌹

Here, we can see a 52-carat sunstone carving by Darryl Alexander, which displays three distinct areas of colour: reddish orange, yellow and green.

It was carved from rough uncovered in the Sunstone Butte mine in Harney County, Oregon, which also exhibits the Schiller effect (also known as aventurescence) caused by reflective copper platelets.

📸 Courtesy of Darryl Alexander.

Gem-A Members can read the latest issue here:


The Gem-A team has had a wonderful time at the Scottish Gemmological Association Conference 2024! 🏴󠁧󠁢󠁳󠁣󠁴󠁿

As a sponsor, we were pleased to participate in this great event and network with members of the Gem-A Community. Well done also to Gem-A tutor Pat Daly for delivering an insightful workshop on screening coloured gemstones.

Here’s a shot of Henry Mesa, our administration and logistics officer, and Anita Matharu, manager of Gem-A Instruments, who were on-site alongside other members of the Gem-A Team.

Did you attend the Conference this Bank Holiday weekend? Share your highlights in the comments…


Did you see this phenomenal picture in the latest Gems&Jewellery magazine? ⭐️

The Spring 2024 edition showcases this rutile star with a titanium-rich hematite/ilmenite core housed within a smoky quartz from Brazil.

📸 This photomicrograph was captured by Nathan Renfro (field of view 18.00 mm), while the stone was courtesy of the John Koivula Inclusion Collection.

Gem-A Members who are curious about how these incredible inclusions grow in nature can read the issue here:

Discover how to access our magazines:


Let’s talk about tabby extinction… 👊

When a synthetic Verneuil flame fusion spinel is observed between polarising filters of the polariscope, it displays captivating patterns of light and dark bands with a cloudy appearance.

This phenomenon occurs due to the orientation of the crystal structure and the excess amounts of aluminium oxide within it.

This unique display is called tabby extinction, another form of Anomalous Extinction Effect and is a diagnostic feature for this synthetic material.

📸 Gabriel Kleinberg.

Find out more about our world-renowned courses, including the Gemmology Foundation:

Photos from Gem-A's post 30/04/2024

What makes red diamonds so rare? 🧐

Gem-A tutor Pat Daly dives into the elusive world of red diamonds over on the Gem-A GemHub.

Pictured here are some well-known red diamonds, including the DeYoung Red, the Argyle Everglow, and the Kazanjian Red.

📸 Images belong to the Smithsonian National Museum of Natural History, Rio Tinto, and Kazanjian.

Read more here:


Don’t miss this fantastic professional development one-day workshop with Branko Deljanin FGA DGA 💎

Learn to identify natural, treated, and synthetic colourless diamonds, and bolster your skills in screening for various colour and clarity enhancements.

Please note that this event is suitable for intermediate to advanced-level gemmologists, jewellers and valuers.

Gem-A London | July 15, 2024 | 09:00 - 17:30 GMT

View all upcoming events:

📸 Finer crosshatching of weak and strong anomalous birefringence in CVD-grown diamond.


Here’s an interesting calcite specimen in the Gem-A Gemstones & Minerals Collection 🔍

Did you know? Gem-A Members and Students can speak to us about reviewing stones in the Gem-A Collection for research purposes or to aid their studies.

With some advance notice, Members can also access our on-site gemmological library and browse our magazine archives.

There’s more to being a Gem-A Member. Find out more here:

Want your school to be the top-listed School/college in London?

Click here to claim your Sponsored Listing.

Videos (show all)

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💡 Gem-A Conference 2023 – Speaker Spotlight 💡  Professor Andy Shen will be joining us at the Gem-A Conference to discuss...
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