Current Turnaround Time at the AGTA GTC
5-7 business days


Paraiba tourmaline Paraíba
An examination of this important gem variety.


Full Articles


JCK Vegas

Las Vegas show AGTA GTC at the Vegas Show
We take our Mobile Laboratory on the road to the Las Vegas JCK Show.
8.62 ct. ruby Beryllium-Treated Blue Sapphires
The latest developments on this new treatment.
Red Fruit Seeing Red
Do male vs. female genetics play an important role in human color vision?
New Zealand Sapphires New Zealand Sapphire
Kiwi corundums in the spotlight.
Flux Healing The Synthetic Healing of Ruby
A misunderstood ruby treatment exposed.
Regente Pearl Passport to Obscurity
Inclusions as passports. Also the sale of the Régente pearl.
Madagascar Sapphire Madagascar!
An eyewitness exploration of Madagascar's important ruby and sapphire mines.
Colombian emeralds Colombia's La Pita Mines
A visit to one of Colombia's most important emerald mines.
Raman Spectrometer Introducing our Instruments: The Raman Spectrometer
We examine a powerful analytical technique. Also an update on the LMHC meeting in Lucerne.
Blue Filter Proletarian Gemology: The Blue Filter
A look at a simple technique for identifying yellow sapphires.
Green Filter Seeing in the Dark 3: The Green Filter
Part 3 of this article on the use of UV light to detect heat treatment.
Also: UV-VIS spectrometer.
Verneuil boules Dangerous Curves: Verneuil Synthetics Reexamined
A closer look at the most common type of synthetic corundum.
Also: Dr. Lore Kiefert lectures to Raman conference.
Covellite in Quartz AGTA GTC's Koivula & Hughes Lecture in New Mexico
The West Coast team lectures to a radiation conference.
Glass-filled star ruby Glass-Filled Star Ruby
An examination of a brand new treatment.
tanzanite crystal Huge Tanzanite Crystal Discovered
Tanzania yields yet another magnificent treasure.
trapiche emerald Unusual Trapiché Emeralds
The AGTA GTC examines two unusual trapiché emeralds.
fiber optic light Living in the Dark Ages: The Fiber-Optic Light Source
A number of stunning images illustrate the utility of this gemological tool.
padparadscha Pretty price for padparadscha
This 20.84-carat padparadscha sapphire recently fetched $18,000/ct. at auction.
rutile silk Following the Silk Road: Rutile silk in corundum
Love letters in honor of rutile silk.
Also: GemmoBasel 2005 Conference.
uv fluorescence Seeing in the Dark 2: UV fluorescence as a gem dealer’s tool
A further look at the powerful technique of UV fluorescence.
symmetry Inside Out: Crystal symmetry and inclusions
A gorgeous photo essay on how internal and external symmetry are related.
uv fluorescence Seeing in the Dark: UV fluorescence as a gem dealer’s tool
Simple, inexpensive and powerful. We take a look at this important but neglected technique.
demantoid cat's eye Idol’s Eyes
Rare demantoid cat’s eyes put under the microscope at the AGTA GTC.
Also: Inclusion Corner.
ruby record Ruby sets new auction record
The gem world was abuzz with the news that a new auction record had been set for ruby at a recent Christie's sale.


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