Gem-A

What are the ‘Cardinal Gems’? 🧐

As Pat Daly FGA DGA explains on the Gem Hub, this term can be used to spotlight five gemstones – diamond, ruby, sapphire, emerald and amethyst – on the grounds that they had special significance, preciousness and value in classical Roman, Greek, Egyptian and Mesopotamian cultures.

Read more on the Gem-A Gem Hub: https://gem-a.com/gem-hub/gem-knowledge-what-are-the-cardinal-gems/

Are you ready to start your gemmology journey?

💻 Learn online, in your own time and at your own pace with GemIntro: https://gemintro.gem-a.com/

The Copper Connection: Identifying Oregon Sunstone 💻

Don't miss this fantastic webinar on Wednesday, July 15, hosted by Rosie Young BSc FGA EG. Discover the role that copper plays in Oregon sunstone and the processes responsible for its distinctive colour zoning and schiller.

This insightful session will cover the geology of the deposit and Oregon sunstone mining, before discussing copper diffusion-treated andesine and the key features used to distinguish treated material from natural sunstone. Comparisons will also be made between copper-bearing sunstone from Ethiopia and material from Oregon.

📸 Features of Oregon sunstone, including copper schiller in reflected light (FOV 5.14mm), a ‘dust devil’ (FOV 3.57mm) and sunstone ‘wires’ (FOV 4.79mm). All photographs courtesy of Rosie Young.

Register to attend this great webinar here: https://gem-a.com/event/identifying_oregon_sunstone/

Kyanite is one of the most recognisable minerals found in metamorphic rocks, occurring as elongated crystals that can range from pale blue to deep blue in colour 💙

The specimen shown here illustrates kyanite in its natural geological environment, where crystal growth has taken place during regional metamorphism deep within the Earth’s crust.

Kyanite forms under conditions of high pressure and relatively moderate temperature, making it an important index mineral for geologists. Its presence can provide valuable information about the pressure-temperature conditions experienced by the host rock during metamorphism.

From a gemmological perspective, kyanite is perhaps best known for its pronounced anisotropic hardness. The hardness measured parallel to the length of a crystal differs significantly from that measured across it, a property that presents unique challenges during cutting and polishing.

Studying minerals such as kyanite provides valuable insight into the relationship between geological processes, crystal growth and gemstone formation. Understanding these connections is fundamental to gemmology.

➡️ Applications are now open for our Gemmology Foundation course, starting in September 2026. Designed for aspiring gemmologists and jewellery professionals, the course provides a comprehensive introduction to the science of gemstones and the practical skills used in gem identification.

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

📸 Gabriel Kleinberg

Back by popular demand! Join our next pearl stringing workshop 🦪

Limited spaces remain for our pearl stringing masterclass, led by Anja Mohler FGA.

Join us at Gem-A London on October 17 for practical tips and tricks tailored to beginners.

At the end of the four-hour workshop, you will be able to take home a fully knotted freshwater pearl necklace that you’ve made yourself.

🌟 Don't miss out! Secure one of the few remaining spaces here: https://gem-a.com/event/pearl-stringing-workshop-create-your-necklace/

Discover our full roster of webinars, in-person events and workshops here: https://gem-a.com/resources/events/

The latest edition of The Journal of Gemmology (Volume 40, No. 2, 2026) is now available for Gem-A Members to access online 📚

Highlights of this edition include feature articles on metamorphic blue sapphires, jadeite jade from Kazakhstan, gem-quality hurlbutite from Myanmar, and historic rings set with emeralds from Pakistan.

Did you know? A relatively new and unknown source of iridescent andradite is Niger in West Africa.

📸 On this issue’s cover, we spotlight samples from this locality, including an unpolished crystal cluster weighing 6.3 g and lightly polished stones weighing 10.68, 5.25, 4.42 and 9.02 ct (clockwise from the top). Courtesy of Tyler Kahn (Isometrica, Santa Cruz, California, USA); photo by Robert Weldon.

Gem-A Members can read the issue here: https://gem-a.com/publications/the-journal-of-gemmology/volume-40-issue-2-2026/

Become a Gem-A Member today to start receiving our industry-leading publications and professional resources: https://gem-a.com/membership/

There's still time to complete our 2026 Gem-A Member Survey ✒️

Gem-A Members should have now received an email with a link to a special survey.

In just 15 minutes, you can help shape the future of Gem-A and influence the services, benefits, events, and resources we provide to our global community.

Your feedback is one of the most valuable sources of insight we have, helping us understand what matters most to you, what inspires you, and where we can continue to improve.

As a token of our appreciation, everyone who completes the survey will have the opportunity to enter a prize draw to win one of five £50 Amazon vouchers.

The survey closes on June 25, 2026, so we encourage you to share your views before then.

If you have any questions, please contact us at [email protected].

Star diopside and the phenomenon of asterism ✨

Among the many optical effects observed in gemstones, asterism is one of the most distinctive. This phenomenon occurs when light is reflected from oriented inclusions within a gemstone, producing a star-shaped pattern that appears to glide across the surface as either the stone or the light source is moved.

The gemstone featured here is star diopside, a variety of diopside that typically exhibits a four-rayed star, unlike the six-rayed asterism more commonly associated with corundum varieties such as star sapphire and star ruby.

The asterism observed in star diopside results from dense concentrations of microscopic, needle-like inclusions, commonly magnetite, that are aligned along crystallographic directions within the host mineral. When a strong, focused light source is directed onto the surface, these inclusions reflect light in a manner that produces the characteristic four-rayed star.

To display asterism effectively, the rough must be carefully oriented before cutting so that the inclusions are positioned correctly relative to the dome of the finished gemstone. A cabochon cut provides the curved surface necessary for the reflected rays to converge and form a visible star.

If the material were faceted, the effect would be significantly reduced or lost altogether.

📚 If you’re interested in finding out more about optical effects in gemstones, now’s the perfect time to explore our upcoming Gemmology Foundation course, which starts in September: https://gem-a.com/gemmology-courses/

📸 Gabriel Kleinberg

Take your interest in diamonds to the next level in September 2026 💎

Study our globally recognised Diamond Diploma in person at Gem-A London or via Online Distance Learning to enhance your career or kickstart a new one. You will secure a Gem-A Level 5 Diploma that equips you for the next phase of your professional journey.

Diamond Diploma students learn how to…

💍 Critically assess the ethical, social and environmental impact of diamonds
💍 Discuss issues like conflict diamonds and sustainability with confidence
💍 Grade and value diamonds to a professional standard
💍 Distinguish between natural, treated and synthetic diamonds

Upon completion, Diamond Diploma Graduates can apply to become a Gem-A Member and utilise the DGA post-nominals — a sign of excellence in the trade.

Discover more and apply today via https://gem-a.com/education/study-diamonds/diamond-diploma/

Ask questions about our upcoming courses by emailing [email protected].

Could you be the freelance gemmology tutor we are looking for? 🧐

We are recruiting for a new external assistant gemmology tutor (visiting tutor) to teach evening classes at Gem-A London on a freelance basis.

It is essential that you have a Gem-A Gemmology Diploma and the ability to commit to teaching two nights per week (Mondays and Tuesdays) from September 2026 until July 2027.

The right candidate will have the opportunity to progress to become a lead tutor after training.

Read the complete job description and requirements here: https://gem-a.com/about/careers/external-assistant-gemmology-tutor-visiting-tutor/

Look what we've added to the Gem-A Instruments shop 🔎

We are so pleased to be stocking Internal Features of Gemstones by Valentin Fejoz and Francoise Besset— a fantastic new addition for anyone fascinated by the hidden world inside gems.

This beautifully detailed book is an excellent resource for gemmologists, students and gem enthusiasts alike.

There’s limited availability, so if you want to ensure this book ends up in your collection, now’s the time to make a purchase: https://shop.gem-a.com/product/internal-features-of-gemstones-by-valentin-fejoz-and-francoise-besset/

📚 Remember, Gem-A Members and students receive 5% off all book purchases!

Purchase a complete range of gemmological equipment, comprehensive toolkits, books, accessories and gifts here: https://shop.gem-a.com/