In Memoriam
George Rossman, PhD, 1944–2026, Professor of Mineralogy, Emeritus,
California Institute of Technology [Caltech], died on Friday, February 6, 2026. He was 81 years old.
On Saturday, February 7, Caltech posted a thoughtful and moving tribute to Dr. George Rossman on its website titled “Caltech Mourns the Passing of George Rossman (1944–2026).”
The Caltech tribute to one of its most distinguished professors reflects on Dr. Rossman’s 55-year career at the California Institute of Technology, his pioneering application of Fourier-transform infrared spectroscopy (FTIR), his groundbreaking work on hydrogen in minerals, and the major recognitions that followed — including the Mineralogical Society of America’s inaugural Dana Medal in 2001 and its highest honor, the Roebling Medal, in 2021. It honors a gifted teacher, recipient of Caltech’s Richard P. Feynman Prize for Excellence in Teaching, and a scientist whose work reshaped our understanding of Earth and planetary materials.
But there is one word that does not appear in that tribute.
Gemology.
And yet, for many of us, that is where George Rossman’s impact was most directly felt.
For decades, if you wanted to understand why a gemstone had its color — not just descriptively, but scientifically — you were eventually led to George’s work. In addition, his research on trace elements, color centers, hydrogen in minerals, and the application of Fourier-transform infrared spectroscopy (FTIR) gave gemology something it had long needed: a rigorous scientific framework. He did not simply state that chromium makes ruby red or that irradiation alters diamond color. He explained how and why at the atomic level.
That distinction mattered.
a Secondary Ion Mass Spectrometer used to characterize nano-inclusions in gem materials.
Photo by Brendan Laurs, March 2008.
George helped move gemology beyond observation and into measurable, reproducible science. His work laid the foundation for modern approaches to treatment detection, origin studies, and advanced analytical testing. The widespread adoption of FTIR spectroscopy in gem laboratories — now considered routine — owes much to his early demonstration that this tool could unlock the secrets of complex natural solids, including gems.
He also helped legitimize gemology within the broader scientific community. By applying the same standards of spectroscopy and crystal chemistry used in academic mineralogy to materials cherished in the jewelry trade, he narrowed a gap that had existed for generations. In doing so, he elevated the scientific conversation around gemstones.
GIA, where Rossman served on the Board of Governors from 1995 to 2007 and advised researchers for more than five decades, acknowledged that legacy in its own statement. “George was a skilled and passionate scientist, a dedicated and talented educator, and a mentor to generations of GIA scientists,” said Tom Moses, GIA’s executive vice president and chief laboratory and research officer.
Jennifer Stone-Sundberg, senior technical editor of Gems & Gemology, added that Rossman was “one of the most significant resources for Gems & Gemology, whether he was an author, peer reviewer or guest editor. Endlessly curious, he would always consider a researcher’s background and research capabilities and was very sympathetic to new talent.”
That curiosity and generosity were themes echoed by colleagues across the field.
Dr. Jeffrey Post, Curator, Emeritus, National Museum of Natural History – the Smithsonian Institution’s National Gem and Mineral Collection, and member of GIA’s Board of Governors, noted that Rossman’s “long relationship with and important contributions to GIA are a significant part of his impressive legacy to science, teaching, and passion for minerals and gems and the natural world. This is such devastating news.”
Photo credit: Caltech.
Post goes on to say, “I was fortunate to overlap with George through most of my career and we shared many interests. Every conversation that I had with George was fascinating and a great joy. His genuine enthusiasm on almost any topic related to minerals was both infectious and inspiring.”
“I always knew that whatever topic I approached George with, he would respond with excitement, and this was especially helpful early in my career. He made a great difference in my life and to all of us who study and love minerals.”
“That we were both originally from Wisconsin also made the connection more special. George and I often shared our appreciations for being encouraged to build and experiment with large home chemistry sets in our youth and be able to take advantage of an excellent and then very affordable state university system. He inspired many!”
Shane McClure, GIA’s Global Director of Colored Stone Services, reflected on Rossman’s accessibility and mentorship. “I worked with George many times over the years and I learned a lot from him. I even had the pleasure of going to Caltech some time ago and seeing his office and some of the labs they have there.”
“George was always generous with his time and knowledge and I could call him up or send him an email if I needed his advice on something I didn’t understand or didn’t know,” McClure said. “I learned a lot of what I know concerning the coloration of gems from him and I will always be grateful to him for that.”
“It is a great loss and I will miss not being able to get his advice on some difficult problem or concept in the future.”
Photo credit: Caltech.
Brendan Laurs, Editor-in-Chief of the Gem-A’s Journal of Gemmology, writes “George was a great scientist, educator, and friend, and I will miss him greatly. He had a special ability to explain technically complex subjects in an understandable way to anyone, without making you feel ‘unlearned’. He was an incredibly rare mixture of genius and humility. His expertise on mineral spectroscopy and the origin of colour in minerals was unparalleled, and his Mineral Spectroscopy Server at http://minerals.caltech.edu is clear proof of this, and it will live on as part of his enduring legacy—along with his many high-quality scientific articles and contributions to books and monographs. He also gave wonderful talks at gem and mineral symposia, which were very instructive and informative. I learned so much from George!”
Everyone learned so much from George.
George Rossman’s name appears throughout the gemological literature. More importantly, his influence appears in the way modern gem labs think, test, and teach. His work gave the field stronger footing. That contribution — quiet, methodical, and deeply foundational — will certainly live on.
Dr. George Harlow, Curator Emeritus, Department of Earth and Planetary Sciences, Division of Physical Sciences, American Museum of Natural History, New York, New York.
“George was all about curiosity. I first got to appreciate George Rossman when he was talking at a MSA Short Course on spectroscopy in 1988 where he did one of his “guess what this mineral is” tests before an audience of participants. It was a gem species, and as a curator of both minerals and gems I blurted out peridot, rather than olivine. George smiled and that was when I knew he was a fellow spirit.
George Rossman’s best known contribution in the gemological literature is for the three articles with Emmanuel Fritsch in G&G in 1987-8 on the origin of color in gems. Many have used this as a bible although much deeper inquiries have occurred in this century.
But a big part of George’s contribution was to bring gems to the attention of the scientific community. What would modern gemology do without George’s mind and approach and deep reach into teaching and the academic community. George typically knew the answer to most questions about color in inorganic phases (minerals) or knew the right questions to ask if he did not. But his inclination was to make you ask and think.
I spent the most concentrated time with him when in 2002 we went, courtesy of Bill Larson’s arrangements and participation, to Myanmar and got to the Jade Mine Tract. George was curious and friendly about everything except food. First, he did not imbibe, unlike the rest of us who poisoned ourselves with Dagan beer (or was it formaldehyde) or worse. Next, he got his white food credentials in Wisconsin; spicey Asian food was a challenge. But the fun was being in the field, acquiring rough at the source, wafting some kyat and watching locals run up with their bags of colored stones whether at Namya, Sagin, or Mogaung, where we knew we were not being lied to about source, or in the markets at Mandalay and Yangon where we had to be more careful. Checking rough with George and Loretta Castoro (who was also there) was great fun and a great learning experience.
My most common conversations were with George over the phone when I had a spectroscopic question or one about what he knew of the source of color in amethyst, rose quartz, spinel or jadeite, including carrying out some projects together. Alternatively, it was George asking me whether I had seen a mineral with a particular color or did we (the AMNH) have a particular specimen he could study. Curiosity was the highest calling for both of us, and that endeared him to me. I will miss communicating with him.”
Dr. Emmanuel Fritsch, Ph.D., GG, hFGA, Professor of Physics (Materials Science) at the Institut des Matériaux Jean Rouxel (CNRS), Nantes, France, reflected:
“It was traumatic for me that George left so suddenly. We were in the midst of publishing a major article together on charge transfer. I was also collaborating with him on a paper about orange cordierite, and we had agreed to update the ‘color article’ for Gems & Gemology together.
“It is funny that I have a photo of him on Zoom showing a missing tooth, yet he never mentioned the stomach problems that ultimately took him.
“I loved George because he was so different from most people — always even-tempered, always ready to help the younger generation, students and colleagues alike. He was never critical, always constructive. For me, he was a mentor, someone who helped me become who I am. I owe him a great deal for what he taught me about how to write a scientific article, exemplified by our three-part series on the origin of color in gems — still cited today, nearly forty years later.
“He instilled in me the importance of being demanding in science — to search for two independent lines of evidence rather than rely on one ‘good idea’ that might be too speculative. Because of that, there are dozens of binders in his office filled with unpublished research. I used to tease him about this, but he was simply waiting for the second proof.
“He was absolutely honest — in life and in science. Incredibly modest, he shied away from flattery. I remember him at a conference becoming visibly uncomfortable when two Japanese colleagues told him, ‘Oh, but you are so famous!’ It is fitting that three minerals were named in his honor — variations of rossmanite tourmaline — because he truly loved minerals, especially tourmaline. The only time I ever heard him brag was during a Zoom session when he would ask one of my associates, ‘So, what is the mineral in the picture?’ And when the unsuspecting victim answered, ‘Tourmaline,’ George would reply, ‘Well, it is a rossmanite!’
“George left us too early. I am convinced that if his wife had still been with him — she passed away far too young — he would have had an even greater appetite to continue publishing good science, especially with young researchers. We will try to carry that forward for him, to let the younger generation know what a great person he was, to use him as a model, and to complete the unfinished work we had together.
“Goodbye, George. My life would not have been the same without you.”
at the 19th Annual Sinkankas Symposium in April 2023 at the GIA campus in Carlsbad.
Image courtesy of GIA.
From Bill Larson, president of Pala International, Fallbrook California.
“George was my friend for 55 years, since 1971.
“He brought students to our various mines in Pala, California. Best teacher I have ever met.
“He did wonderful talks at the Sinkankas symposiums. We presented the rare mineral painite together, after a trip we took together to Burma.
“We will miss him terribly.”
Richard W. Hughes, co-founder of Lotus Gemology in Bangkok, reflected:
“George was the consummate scientist. We worked together on a Tibetan andesine project 16 years ago. I always found him to be generous with his time and knowledge. He was committed to science and committed to the truth. I will always remember him for that.
“I also remember him casually asking me, prior to my presentation on Burmese jade at one of the Sinkankas Symposia, whether I would be talking about elephants and my party’s struggle to reach the jade mines during the rainy season in 1996. I told him I would — with perhaps a bit of extra embellishment.
“Then, when George gave his program, he described how he had simply driven there without problem. That little devil.”
“In the affectionate words of his longtime friend Bill Larson, ‘I’ll miss his sorry ass.’ “
Andy Shen, Professor, Gemmological Institute, China University of Geosciences (Wuhan), reflected on Rossman’s scientific and personal impact:
“For nearly six decades at Caltech, George built a unique bridge between rigorous mineral physics and the practical questions gemologists ask at the microscope and spectrometer. His research centered on three themes fundamental to gemology: the origin of color in minerals, the effects of natural and artificial radiation, and the role and behavior of hydrogen in both hydrous and nominally anhydrous minerals. This work provided the scientific foundation behind many color mechanisms and treatments that gemologists rely on today.
Gemologists knew George not only from his papers but also from his generosity with time, instruments, and insight. I saw firsthand how mineral collectors, curators, and laboratory gemologists found in him a collaborator who welcomed their specimens and questions, treating a rare tourmaline or puzzling quartz as an opportunity to advance shared understanding.
George’s service on the GIA Board of Governors from 1995 to 2007 helped embed strong, science-based research within one of the world’s leading gemological institutions, strengthening mutual respect between academic mineralogy and professional gemology. His work with GIA research teams on the role of beryllium in modifying the color of sapphires and on the color origin of red plagioclases shaped major developments in the gem trade over the past two decades.
Remembered as a brilliant scientist and an unfailingly helpful mentor, George leaves a legacy that lives on each time a gemologist explains a color band, a treatment, or a spectrum with confidence grounded in his work.”
Loretta Castoro, Director of Jewelry Verification Services at the Gemological Institute of America and a longtime laboratory gemologist and jewelry designer, shared this memory:
“Bill Larson introduced me to George Rossman and George Harlow during a trip to Myanmar. George Rossman, George Harlow, and I traveled through Namya, Hpakant, and nearby villages on that trip. After rough terrain left most of our vehicles broken down, all eight of us piled into one car, and I spent countless hours sandwiched between the two Georges. Thus, the ‘George Sandwich’ was born. It became a tradition wherever we met — always time for a photo, and if one George wasn’t there, I’d Photoshop him in and send it along.
While in Hpakant, one morning I was woken by a loud crowd of Chinese scientists. Confused by the commotion, I looked out and saw the Georges surrounded by the group. I went downstairs to make sure they were okay, and George explained that a busload of Chinese scientists had recognized them. They were so excited they wanted to talk with them and take photos.
They took pictures at the hotel and then followed us to one of the jade mines. When we arrived at the airport to fly out of the area, the same group — who were traveling by bus — were there waiting to take more pictures of the Georges. They were true rock stars.
I was truly blessed to have George as a friend. I will miss him deeply and always cherish our time geeking out over gems and minerals.”
On a personal note: I never worked with George on major gemological studies, joined him on mining expeditions or trips to Burma, nor visited him at Caltech. But when I needed to understand the science behind a treatment — to truly understand it — George was at the top of the list.
He would not simply give me an answer to the question at hand. He was a professor in the truest sense — teaching, asking questions, making me think and work towards the answers. Never impatient with my lack of understanding, or my sometimes overly simplified view of an enhancement, George was there for all of us.
And we will miss him immensely. – gr
Professor of Mineralogy
Champion of Gemology
Photo Credit: Caltech
George Rossman leaves behind a scientific legacy that will endure in laboratories and classrooms around the world — and in the memories of those who had the privilege to work beside him.
Special thanks to Emily Velasco, and Brendan Laurs for their assistance with this memoriam for George.
