Gems & Gemology, Winter 2025, Vol. 61, No. 4

Converge 2025 GIA Hands-On Sessions

GIA Staff

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Figure 1. Left: James Shigley presents on the unique story of natural diamond. Right: A kimberlite eruption plucked this 52.45 ct diamond octahedron from deep below the earth’s surface, where it might have rested for billions of years. Photos by Emily Lane (left) and Robert Weldon; courtesy of the GIA Sir Ernest Oppenheimer Student collection (right).
 
Figure 1. Left: James Shigley presents on the unique story of natural diamond. Right: A kimberlite eruption plucked this 52.45 ct diamond octahedron from deep below the earth’s surface, where it might have rested for billions of years. Photos by Emily Lane (left) and Robert Weldon; courtesy of the GIA Sir Ernest Oppenheimer Student collection (right).

Hands-on sessions afforded Converge attendees the opportunity to learn from GIA experts and work with samples from the Institute’s extensive reference collection.

The Natural Diamond Story: Natural and Laboratory-Grown Diamond Differentiation

Dr. James Shigley (GIA, Carlsbad) presented a session focused on the incredible geologic story of natural diamond, reminding participants what a remarkable mineral diamond is (figure 1). He explained that the gem’s origins provide jewelry professionals with memorable and relatable information they can use to educate consumers on the value of mined diamonds, to differentiate natural from laboratory-grown, and to address common misconceptions about abundance, mining practices, corruption, and human rights abuses. In this practical session, Dr. Shigley covered key aspects of natural diamonds’ value and rarity, including their incredible geologic age and remarkable formation process, along with how and when they arrived at the surface through kimberlite eruptions. He explained how geologists search for viable diamond deposits and mining companies recover these diamonds, also providing an outline of the world’s significant mines and their projected remaining production years. Also covered were the many positive micro and macro social benefits to communities involved in diamond mining, as well as environmental impact and sustainability. Dr. Shigley explained what is currently scientifically possible in terms of determining the geographic origin of a natural mined diamond—also covered by GIA’s Dr. Michael Jollands in a speaker presentation—and outlined GIA origin services. Participants were able to handle natural and lab-grown rough and faceted gems and use their microscopes to examine interesting natural inclusions.

Beauty in Unexpected Places: The New Frontiers of Ruby and Sapphire

In this hands-on seminar, Dr. Aaron Palke (GIA, Carlsbad) and Wim Vertriest (GIA, Bangkok) provided an in-depth report on rubies and sapphires from lesser-known deposits including the United States (Montana), Tanzania, Kenya, Afghanistan, Sri Lanka, and Greenland (figure 2). They demonstrated practical tips for identifying corundum from these alternative deposits and gave context for understanding the place of these gems in the complex global colored stone trade. Participants were able to examine ruby and sapphire samples from the GIA colored stone reference collection representative of these newer localities and hear directly from the field gemologists who visited the areas and collected the gems.

Figure 2. Left: Wim Vertriest outlines key characteristics of gem corundum from less familiar localities in a session held during Converge 2025. Right: Attendees use their cell phones to capture images of intriguing inclusions. Photos by Emily Lane.
 
Figure 2. Left: Wim Vertriest outlines key characteristics of gem corundum from less familiar localities in a session held during Converge 2025. Right: Attendees use their cell phones to capture images of intriguing inclusions. Photos by Emily Lane.

(Un)Natural Beauty: Treatments in Ruby and Sapphire and Their Identification

It is increasingly rare to come across ruby and sapphire with beauty and appeal entirely due to natural processes. The majority of stones on the market have been treated to enhance their appearance. In this hands-on seminar, GIA’s Dr. Aaron Palke and Wim Vertriest provided an in-depth orientation into the various artificial treatments for ruby and sapphire (figure 3). Using samples from GIA’s colored stone reference collection, participants learned practical tips for identifying these treatments and gained an understanding of their value.

Figure 3. Aaron Palke helps orient a treated gemstone under the microscope for seminar attendees to view its diagnostic inclusions. Photo by Emily Lane.
 
Figure 3. Aaron Palke helps orient a treated gemstone under the microscope for seminar attendees to view its diagnostic inclusions. Photo by Emily Lane.

Photomicrography of Gems

Inclusions in gemstones often captivate gemologists with their natural beauty. In this session, Nathan Renfro (GIA, Carlsbad) demonstrated that inclusions can also provide valuable information about gems, including what they are and whether they are treated, natural, or synthetic (figure 4). Renfro presented various lighting control techniques used to significantly enhance photomicrographs. He focused on a variety of interesting gemstone inclusions, encouraging participants to use their cell phones to practice some of the lighting techniques covered. Renfro explained that documenting observations with a photograph is a useful method of recording inclusions that is easily shared with others. Photomicrographs appeal to a broad audience, from those who are interested in the hidden beauty of the natural world to an appraiser who uses inclusions as a “fingerprint” to document the identity of a unique stone.

For more information, see Renfro N. (2015) Digital photomicrography for gemologists. G&G, Vol. 51, No. 2, pp. 144–159, http://dx.doi.org/10.5741/GEMS.51.2.144

Figure 4. Left: Nathan Renfro delivers practical hints and tips to seminar participants. Right: Attendees viewed inclusion scenes like these golden yellow rutile needles in rock crystal quartz. Photos by Emily Lane (left) and Nathan Renfro; field of view 7.61 mm (right).
 
Figure 4. Left: Nathan Renfro delivers practical hints and tips to seminar participants. Right: Attendees viewed inclusion scenes like these golden yellow rutile needles in rock crystal quartz. Photos by Emily Lane (left) and Nathan Renfro; field of view 7.61 mm (right).

Introduction to Jewelry Forensics

While jewelry appraisers, those who take in jewelry for repair, and buyers of used jewelry go through a process to identify, analyze, and assess the quality and nature of a jewelry item, it is often not as comprehensive and systematic as they might wish. Many know only certain aspects of manufacturing and are only able to recognize a narrow range of specific characteristics. In this lecture and hands-on seminar, GIA Carlsbad’s David Etheridge and Al Gilbertson guided participants through a systematic GIA framework to help them recognize and identify basic characteristics of key manufacturing processes (figure 5). They demonstrated the fundamentals of jewelry forensics, including identifying hand-fabricated, cast, and CAD/CAM-manufactured components, as well as cast-in-place gemstones.

Figure 5. Left: Al Gilbertson provides an introduction to jewelry forensics. Right: Attendees inferred manufacturing processes and likely provenances for jewelry pieces like this platinum and gold Edwardian brooch. Photos by Mimi Travis (left) and Robert Weldon; courtesy of Brian Davenport (right).
 
Figure 5. Left: Al Gilbertson provides an introduction to jewelry forensics. Right: Attendees inferred manufacturing processes and likely provenances for jewelry pieces like this platinum and gold Edwardian brooch. Photos by Mimi Travis (left) and Robert Weldon; courtesy of Brian Davenport (right).

Advanced Gemological Testing Workshops at GIA

Three sessions of an advanced gemological testing workshop were offered during the GIA Open House on September 7 as part of Converge 2025. Developed and led by Dr. Tao Hsu (GIA, Carlsbad), the two-hour workshop provided an overview of and hands-on experience with the six core advanced testing techniques commonly used in gemological laboratories: ultraviolet/visible/near-infrared, Fourier-transform infrared, Raman, and photoluminescence spectroscopy along with an X-ray fluorescence analyzer and a DiamondView. Together these techniques aid in the accurate identification of diamonds, colored stones, and pearls. The reliability and accessibility of these instruments make them viable tools for students. Some of these instruments are portable and could potentially be used in small businesses.

Each session opened with a lecture on the basic principles and major applications of the six techniques. Then students participated in hands-on activities in pairs. At each activity station, an instructor guided students through the testing process before they conducted their own analyses using select samples showing the main applications, strengths, and limitations of each instrument.

Many participants were GIA Graduate Gemologists with extensive trade experience (figure 6). The workshop helped refresh their knowledge and enhance their understanding of advanced gemological testing. Some participants noted that the workshop clarified questions about the advantages and limitations of these techniques.

Following the success of the workshop, GIA Education continues to develop this program to meet the demand for more in-depth gemology education.

Figure 6. Attendees of the first session of GIA’s advanced gemological testing workshop held during Converge 2025, along with workshop developer Tao Hsu and six instructors from the Carlsbad education team. Photo by Russel Samson.
 
Figure 6. Attendees of the first session of GIA’s advanced gemological testing workshop held during Converge 2025, along with workshop developer Tao Hsu and six instructors from the Carlsbad education team. Photo by Russel Samson.