Research

GIA Colored Stone Research


The World of Colored Stones

Fine, precious gemstones have been objects of desire through all of human history, and the most important quality factor driving this has always been one thing – color. Precious rubies, sapphires, and emeralds are the most important in the modern fine jewelry market. From the ruby mines in Burma to deposits of emeralds in the mountains in the New World in Colombia, empires would rise and fall in the pursuit of these stones. Still, the colored gemstone world is composed of a huge diversity of gem species with stones available to bring color to anyone. From tourmaline to garnets, opal to turquoise, the tastes of modern consumers is also expanding in favor of colored stones besides the “big three”.
GIA’s laboratory services for colored stones include material identification, treatment detection, and geographic origin determination. Identification and origin reports offered by the gemological laboratory at GIA are supported by more than 90 years of unparalleled research and use of the most advanced analytical technology available at only the most elite research institutions.

Colored Stone Sources – Legend, lore, and traceability

Mogok, Burma
Fine rubies came mostly from Mogok in Burma and emeralds were sourced only from Egypt until new stones were found in the New World in Colombia.

In the ancient world very few deposits of precious stones were known. Fine sapphires found in ancient Roman artifacts essentially only came from one source, the gem bearing island of Ceylon (Sri Lanka). Similarly, fine rubies came mostly from Mogok in Burma and emeralds were sourced only from Egypt until new stones were found in the New World in Colombia. The modern age has seen an enormous expansion in gemstone sources and today some of the world’s finest rubies, sapphires, and emeralds come from Mozambique, Madagascar, and Zambia. With growing demand for transparency and traceability for luxury good like colored gemstones, the laboratory at the Gemological Institute of America has stepped in to provide geographic origin determination services on many commercially important gems including ruby, sapphire, emerald, alexandrite, copper bearing Paraiba tourmaline, and red spinel. The following articles give an overview of geographic origin determination for colored stones.

Field Gemology

Researchers in the Field

For more than a decade GIA has sent experienced gemologists and researchers into the field to remote locations, collecting gemstones as close to the source as possible. The underlying philosophy to the creation of GIA’s field gemology department is that the greatest researchers in the world and the most advanced technology cannot lead a gemological research program without a robust, reliable reference collection. Since the 2000s, GIA’s field gemologists have launched numerous field expeditions to gem-producing countries collecting rubies, sapphires, emeralds, and other stones directly from the mines and the miners who recover these fine stones. The materials collected have become the core of GIA’s extensive Colored Stone Reference Collection which forms the foundation of all of GIA’s colored stone research activities and supports Identification and Origin Determination Reporting in the lab. Read more about GIA’s Field Gemology Department in the following links.

Articles

Webinars

The Fascinating Microworld of Colored Stones

inclusions in a saphire

The microscope is one of the most important tools for a careful gemologist. Unbeknownst to the casual observer, there exists a fascinating and visually stunning microscopic world inside many precious stones. The various internal features, called inclusions, inside gemstones not only provide clues to their geographic origins or their potential treatment history, but with the use of modern digital cameras, a gemologist can create aesthetically striking images called photomicrographs. The following links provide a first glimpse into the MicroWorld of Colored Stones.

Colored Stone Treatments and Identification

colored stones

Many colored stones only ever reach the fine gem and jewelry market due to artificial treatments taken out on the stones after they were recovered. In fact, colored stones that have exceptional clarity and color directly after being pulled from the earth can be quite rare, especially for the big three colored stones – ruby, sapphire and emerald. Treatments vary from the use of high temperature furnaces to improve color in sapphires, the introduction of artificial fluxes or glass to improve the clarity of rubies, or the use of polymers, resins or oils to hide fractures in emeralds.

GIA’s Colored Stone Research team is actively focused on developing new techniques to identify treatment more efficiently and accurately so that the GIA laboratory can confidently identify potential treatments in colored stones coming through for Identification Reports. The lab at GIA has had to introduce highly advanced, world-class analytical facilities for treatment identification from Fourier Transform-Infrared Spectroscopy (FTIR) for heat treatment identification to Laser Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS) for detection of beryllium diffusion in sapphires. Researchers at GIA also operate an experimental heat treatment facility, enabling fundamental research into the physics and chemistry of heat treatment in rubies and sapphires among other stones. The knowledge gained from these experiments helps the lab proactively predict new types of treatments that may be possible it he colored stone market. Read more about colored stone treatments and the analytical instruments used to detect treatments in the following links.

Learn more here about advanced research instruments.

Colored Stones Unearthed – The Geology of Gemstone Formation

Colored Stones Unearthed

Fine, precious colored stones are exceptionally rare, formed only under very specific natural conditions. The forces of geology needed to form these precious stones occur only in very specific circumstances, only in very narrow windows of geological time. Some of the world’s most valuable colored stone deposits formed in only two geological events. The first such event involved the collision of east and west Gondwana from around 650-500 million years ago, creating colored stone deposits throughout East Africa and in Sri Lanka. The second event occurred again in a tectonic collisional event with the closure of the ancient Tethys Sea and the collision of the Indian subcontinent with Asia forming the Himalaya Mountains and many deposits of ruby, sapphire, and other stones. A new editorial column covering the geology of gem deposits, Colored Stones Unearthed, is published twice a year in GIA’s scholarly journal, Gems & Gemology. Read more about the fascinating geologic story of these gems in the links below.