Gem-A

This month’s birthstone is the incomparable ruby 🔴

It is important to watch out for rubies that have been fracture-filled with lead glass to improve colour and clarity.

This leaves tell-tale signs, so look for surface-reaching fractures, a difference in surface lustre between the glass and the ruby, and a blue flash within the ruby, as well as bubbles, both of which are confined to the fractures inside of which the glass sits.

It is not advisable to heat these rubies as the lead glass has a low melting point and will leak out of the stone.

📸 A bubble inclusion and iridescence in a glass-filled treated ruby in direct light. Photographed by Pat Daly.

Are you looking for a summer challenge from the comfort of your own home?

Study our GemIntro course online and in your own time for an Ofqual Level 2 qualification: https://gemintro.gem-a.com/ 💻

Chrome tourmaline from Landanai, Tanzania 🌍

East Africa is the main supplier of gem-quality ‘chrome’ tourmaline, and one of the most important sources is the Landanai area of east-central Tanzania.

In December 2024, rough stone dealer Farooq Hashmi visited a deposit known as ‘Commander’s mine’. Several miners were active there, and they used a cable system to transport sacks containing tailings from the mine workings to the surface.

One of the first significant finds from these new workings consisted of a large block weighing 160 kg that contained numerous well-formed crystals. Hundreds of kilograms of ‘chrome’ tourmaline were subsequently produced from there, along with some ‘golden’ yellow tourmaline, which is found within the cores of green crystals or as separate pieces.

The largest gem-quality rough reportedly weighed up to 100 g, but the largest clean pieces seen by Hashmi were in the 10–15 g range.

📸 This 43.93 g rough ‘chrome’ tourmaline was recently produced from the Landanai area. Photo courtesy of Dudley Blauwet.

Gem-A Members can read more via the latest edition of The Journal of Gemmology: https://gem-a.com/publications/the-journal-of-gemmology/volume-39-issue-6-2025/

'Red-cap' Amethyst from Thunder Bay, Canada 🔴

A Gem Note in the latest edition of The Journal of Gemmology explores an interesting type of amethyst from Canada, commonly marketed as ‘Auralite 23’. This is also called ‘red-cap’ amethyst in the Chinese market.

The crystal terminations show a red colour, which creates an interesting contrast with the underlying purple amethyst. It comes from the well-known amethyst deposits in the Thunder Bay area, north of Lake Superior in Ontario, Canada.

📸 An amethyst specimen with well-developed rhombohedral faces (partially covered by a brown coating) with a distinctive red appearance. Photo by J. Yao.

Gem-A Members can read more: https://gem-a.com/publications/the-journal-of-gemmology/volume-39-issue-6-2025/

Can you guess what these materials are? 🔍

Here are some new specimens joining our artificial materials collection, which forms part of the Gem-A Archives.

Just for fun, can you predict what we might be looking at here?

Normally, we would never recommend judging a material by a photo alone, but sometimes it's good to give it a try!

Thank you to our Collection Curator and Gemmology Tutor Judy Zhang for sharing these latest additions and putting us to the test.

Answers will follow in the comments later this week…

Trapiche pink sapphire from Tajikistan 🔬

During the February 2025 Tucson gem and mineral shows, Peter Lyckberg was surprised to encounter an impressive sample of trapiche pink sapphire with beautifully symmetrical and sharply developed arms against a pleasing purplish pink background.

The dark-coloured arms were formed by a dense aggregate of minute inclusions, some showing reflections that might be expected from graphite platelets. The interstitial segments consisted of purplish pink sapphire with subtle hexagonal colour zoning.

📸 This trapiche pink sapphire is reportedly from Tajikistan and shows a well-developed trapiche structure. The stone weighs 11.78 ct and measures 19.17 × 16.26 × 3.20 mm. Photo by Jeff Scovil.

Gem-A Members can read more in the latest issue of The Journal of Gemmology: https://gem-a.com/publications/the-journal-of-gemmology/volume-39-issue-6-2025/

Fayalite inclusion in Guatemalan jadeite-omphacite jade 💚

Jadeite-omphacite jade (fei cui) enjoys immense popularity—especially in the Chinese market—and in recent years, material sourced from Guatemala has seen a marked surge in demand.

A reliable Guatemalan jade supplier recently submitted a jade pendant to Guild Gem Laboratories for provenance analysis.

The stone exhibited a richly saturated green hue with even colour distribution, and microscopic examination revealed a fine-grained texture punctuated by several tiny, dark, irregular inclusions—a characteristic that is diagnostic of Guatemalan jadeite.

📸 This surface-reaching dark inclusion in the jadeite-omphacite was identified as fayalite with amorphous carbon. Photomicrograph by Kaiyin Deng; image width 2.0 mm.

Gem-A Members can read more: https://gem-a.com/publications/the-journal-of-gemmology/volume-39-issue-6-2025/

New in stock at Gem-A Instruments 🔦

This single-arm fibre optic light is back on our digital and physical shelves. It provides high brightness, low power consumption, and light concentration for easy operation.

In these pictures, we are comparing an older torch to the fibre optic light source so you can see the difference. It’s easier to position, more flexible and noticeably brighter.

We recommend this device when precision and reliability really matter… which is all the time!

Shop now: https://shop.gem-a.com/product/fibre-optic-light-single-arm/

Big things are happening tomorrow! 🌟

Good luck to all the candidates taking this year’s FEEG examinations, which include both a theoretical and a practical element.

Gem-A London will host this prestigious test simultaneously with other FEEG Teaching Centres across Europe, including the Austrian Gemmological Association, the German Gemmological Association (DGemG), the Spanish Gemmological Institute (IGE), the French Gemmological Laboratory (LFG), the Royal Belgian Society of Gemology, and the Italian Gemological Institute (IGI).

Gem-A is a founding member of FEEG and is one of just 12 recognised Teaching Centres.

Many of our Gemmology Diploma graduates go on to pursue FEEG qualifications as part of their continuing professional development.

Find out more here: https://feeg-education.com/en/teaching-centres

We have everything crossed for you! 🤞

Your next opportunity to take these exams is in October 2025. Get in touch with us via [email protected] if you would like to find out more.

You’ve powered through lectures, late nights, and deadlines. Now it’s time to raise a glass… with a stirrer worthy of the effort ✨

This isn’t just a fancy accessory. It’s a synthetic ruby rod created by the zone melting technique. A method of purification and single‑crystal growth where a narrow molten region is passed along a sintered rod.

As this liquid region travels, impurities migrate into it and concentrate at one end, leaving a highly pure recrystallised material behind.

These are the same types of crystals used in the cores of industrial lasers, from cutting and drilling to engraving everything from quartz to diamonds with incredible accuracy.

What begins as dust becomes a laser-ready crystal, hot enough for tech, cool enough for a cocktail.

Congratulations on your persistence throughout this examination period. We hope you are pleased with your efforts and get the payoff you deserve.

The Gem-A Collection is an ever-evolving assortment of natural gemstones, artificial materials and interesting specimens that can be used to aid our teaching 🔍

Here, Collection Curator and Gemmology Tutor Judy Zhang spotlights a beautiful opalised snail with purple and orange iridescence from our archives.

Most gem-quality opal forms in sedimentary rocks. Many of these were marine or lake sediments within which shells, bones and wood were sometimes buried and preserved. Most commonly, opal has filled the spaces that remained after these fossils were dissolved; the opal acquired its shape simply because it filled the spaces created by shells or other organic remains.

More rarely, organic structures can be well preserved. For example, buried wood may be preserved if it becomes waterlogged in seas or lakes. Water may deposit minerals in the wood, and they can replace organic structures in remarkable detail if the process is slow and gradual.

🐌 Read more about opalised materials here: https://gem-a.com/gem-hub/opalized-fossils-pseudomorphs/

The latest edition of The Journal of Gemmology (Volume 39, No. 6) is now available for Gem-A Members to download 📚

Discover in-depth feature articles about a new discovery of common opal in north-western Madagascar, factors influencing the UV fluorescence and colour of red spinel from Myanmar, and väyrynenite reportedly from Nigeria.

📸 This issue’s cover features two gold necklaces containing octahedral Burmese spinel crystals along with loose faceted spinels weighing 2.03–3.74 ct from Mogok and Namya (or Nanyaseik). Courtesy of Bill Larson and family; photo by Mia Dixon.

Gem-A Members can access the issue here: https://gem-a.com/publications/the-journal-of-gemmology/volume-39-issue-6-2025/

To become a Gem-A Member and start receiving our magazines, email [email protected].

There’s still time to celebrate moonstone, one of three recognised birthstones for the month of June 🌕

Moonstones are a variety of the mineral feldspar, typically composed of orthoclase and albite. As the mineral cools, these two types of feldspar separate into stacked layers.

When light enters the stone, it scatters between these microscopic layers, creating a visual effect known as adularescence—a soft, billowy glow that appears to float beneath the surface.

This phenomenon is strongly directional, meaning that it is only seen when the stone is illuminated and viewed from specific directions. It is most prominent in high-quality moonstones, particularly those with a blue sheen.

Discover more on the Gem-A GemHub: https://gem-a.com/gem-hub/understanding-moonstones-and-adularescence/