The Myths, Legends and Controversy Behind Ancient Preseli Bluestone

The Myths, Legends and Controversy Behind Ancient Preseli Bluestone

Sarah Steele FGA DGA discusses the unusual history of ancient Preseli bluestone.  If ever there was an unlikely candidate for a gem material then Preseli spotted dolerite, would at least at face value, be it. Over the last five or six years however it has appeared on the market in increasing quantities, both as jewellery and […]

A Passion For Working Fire Obsidian

A Passion For Working Fire Obsidian

Tom Dodge, a retired geologist living in Arizona, USA has been an avid rock collector for 57 years, a registered professional consulting exploration geologist for 35 years, a skilled flint knapper for 16 years and a budding lapidary for two years. Here, he takes a look at fire obsidian, an enchanting and little-known material. Collecting and working fire obsidian […]

Birthstone Guide: Aquamarine for Those Born in March

Birthstone Guide: Aquamarine for Those Born in March

Those born in March are lucky enough to have two birthstones: the beautiful blue of aquamarine and the mysterious red-spotted bloodstone. Here, we delve into the history and mystical properties of aquamarine and why this sky blue gem is said to be a talisman of good luck, fearlessness and protection.  The blue hues common to this […]

Ruby and Pink Sapphire from Aappaluttoq, Greenland

Ruby and Pink Sapphire from Aappaluttoq, Greenland

This article by Guy Lalous ACAM EG summarises a study of the geology, gemmological and physical properties of rubies and pink sapphires from Aappaluttoq, one of the last pristine spots on the planet not far from the arctic circle.  What is the difference between metamorphism and metasomatism? When rocks change because of an increase in […]

Field Trip: Exploring the Wonders of Myanmar

Field Trip: Exploring the Wonders of Myanmar

Gem-A member Patricia Campion reports on a recent gemmological field trip to Myanmar, highlighting her experiences of gemstone market places, the Myanmar Gems Museum, in Yangon, and seeing mushroom tourmaline for the first time. On Christmas Day, our group met in Yangon for a gemmological tour of Myanmar organised by Pauline Jamieson for the Scottish Gemmological […]

The Tale of the Mouawad-Tereschenko Blue Diamond

The Tale of the Mouawad-Tereschenko Blue Diamond

Jack Ogden FGA looks into the story of the world’s second largest blue diamond, the Mouawad Blue Diamond, previously known as the Tereschenko Blue Diamond.  In the summer of 1984 David Warren, now Senior International Jewellery Director at Christie’s, received a phone call from the auction house’s bank manager with a question: “Do Christie’s sell […]

Whitby Jet: A Discussion of its Simulants

Whitby Jet: A Discussion of its Simulants

Sarah Steele FGA DGA discusses the many simulants of one of Britain’s most famous native gemstones, Whitby jet. If imitation is the sincerest form of flattery, then Whitby jet must be a very desirable material indeed. I can think of perhaps 20-30 different materials, both natural and synthetic, which, at one stage or another over […]

An Interview with Dr Jeffrey Post of the Smithsonian Institution

An Interview with Dr Jeffrey Post of the Smithsonian Institution

Claire Mitchell FGA DGA talks to Dr Jeffrey Post, chairman of the Department of Mineral Sciences and curator of the National Gem and Mineral Collection at the Smithsonian Institution, about advanced gem testing, the Hope diamond and the importance of donations to the museum. Dr Jeffrey Post with an assortment of beryls, a tanzanite and […]

Explore the Historic Significance and Mythology of Amethyst

Explore the Historic Significance and Mythology of Amethyst

Amethyst has been worn for its lovely purple colour and mystical properties for thousands of years. From the Ancient Romans to the present day, Julia Griffith FGA DGA EG explores how this beautiful variety of quartz has stood the test of time.  As it is the February birthstone, amethyst has always been linked to love […]

Field Trip: Screening for Tourmaline at the Oceanview Mine, California

Field Trip: Screening for Tourmaline at the Oceanview Mine, California

Claire Mitchell FGA DGA takes a hands-on look at the Oceanview Mine, in the Pala mining district in California, USA. Oceanview Mine is situated 2.5 miles northeast of Pala, on the northeastern slope of Chief Mountain, a short, scenic drive from Pala, California. Visitors to the area pass through landscapes bedecked with nurseries growing a […]

Upcoming Events

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Gemmological Instruments
Meet the Author
Rui Galopim de Carvalho
Thursday, June 5
Decorative plate made of Tortoiseshell which is a material produced from the shells of the larger species of tortoise and turtle.
Gemmological Instruments
Meet the Author
Maggie Campbell Pedersen
Thursday, June 12

Christmas Closure

The Gem-A office will be closed from 3pm Wednesday 24th December 2025 for the holidays, reopening 9am Friday 2nd January 2026.

Season’s greetings from all of us at Gem-A!