The authors
Colombian Emerald / Esmeralda Colombiana is the result of a rare collaboration between five authors, George Smith, Ronald Ringsrud, Geoffray Riondet, Gérard Panczer, and Guilhem Merolle, whose paths converge around a shared fascination for the Colombian emerald, its history, and its light. Together, these five voices weave a complete narrative – human, historical, and scientific — capturing the soul of the Colombian emerald.
Ronald Ringsrud
Ronald Ringsrud is a U.S.-born emerald expert and dealer whose career has unfolded between California and Bogotá for several decades. A chance job in the Gemological Institute of America’s warehouse introduced him to the trade; captivated, he began frequent trips to Colombia, learning the markets and the mines and developing the eye of a field buyer.
His pioneering 1983 article in Gems & Gemology on oil treatment of Colombian emeralds helped the industry discuss enhancement more openly and accurately. Returning to Bogotá as often as six times a year, he built relationships with miners and merchants, educated buyers, and pushed back against myths such as green-tinted oils. In 2013 he joined Muzo International, evaluating stones and supporting international sales as the historic mine modernized its operations. Ron also founded Clayhands, a nonprofit that trains rural youth in low-impact building methods, and his outlook is informed by a respect for nature inspired by the Kogi people.
Author of Emeralds: A Passionate Guide (2010) and The Hardness of Emerald (2025), he divides his time between the United States and Colombia, continuing to trade, write, and share his passion.
George Smith
George Smith is a London-born, Bogotá-based Colombian emerald dealer and founder of Alpine Green. After studies in economics and history and an early career in City finance, a 2013 trip to Colombia set him on a new path. He learned the trade from the ground up—walking the markets, spending time underground in the mines of Muzo and Chivor, and refining an eye for top-grade stones.
Early sales to a leading London jeweler confirmed the shift, and he built a niche supplying exceptional Colombian emeralds to jewelers, designers, and private collectors worldwide. Known for integrity and clear communication, he prioritizes meticulous sourcing, traceability, and fair dealing with miners, often providing mine-of-origin documentation when available.
Headquartered in Bogotá with offices in Miami and Dubai, he works across time zones and markets. On Instagram he shares field notes, mine visits, and selected stones, helping collectors make informed decisions.
Geoffray Riondet
Geoffray Riondet is a gemmologist (HRD, GIA, DU de gemmologie), expert for the Lyon courts, specializing in antique jewelry. He has taken part in the on-site gemmological analysis of numerous historic gems and jewelry pieces, including : Louis XIV’s “Grand Saphir” at the Muséum National d’Histoire Naturelle (2012), Charlemagne’s “Talisman” at the Palais du Tau (2016), Empress Josephine’s coronation ring at the Musée National des Châteaux de Malmaison et Bois-Préau (2016), the crown of Notre-Dame de Fourvière (2016), George Sand’s jewelry at the Musée de la vie Romantique (2017), the Majesty of Sainte Foy de Conques (2017), the Book of Hours of François Ier at the Louvre Museum (2020).
He is also renowned for his ongoing research, publishing numerous articles (over 70 to date) for magazines such as Revue de Gemmologie, Gems & Gemmology and The Journal of Gemmology. Geoffray Riondet is also the author of the book “Bijoux anciens (1800 – 1950). Découvrir, apprécier et identifier”, published by Flammarion in May 2021.
Geoffray Riondet is a professor at the Institut National de Gemmologie. He also lectures at the Université Claude Bernard Lyon 1 as part of the Diplôme Universitaire de Gemmologie.
Gérard Panczer
Gérard Panczer is a professor at Université Claude Bernard – Lyon 1, a researcher at the Institut Lumière–Matière, and head of DUGEM, Lyon’s university diploma in scientific gemology. A physical chemist, mineralogist and gemologist, he has championed portable spectrometry for non-invasive analysis of gemstones in cultural-heritage objects.
Working in situ, he has examined the gemstones of: Roger Caillois’s Académicien’s sword by Jean Vendôme (Musée des Confluences, Lyon); the Pépin shrine (Conques); Catherine de Medici’s pendant (BnF, Paris); Gallo-Roman jewels with rough emeralds (Lugdunum, Lyon; BnF, Paris); Honoré de Balzac’s turquoise cane (Maison de Balzac, Paris); major pieces from Adèle de Rothschild’s collection (Château d’Écouen); the Book of Hours of Francis I (Louvre, Paris); and the Talisman of Charlemagne (Reims).
All of these investigations have resulted in publications or formal institutional reports, reflecting Panczer’s commitment to rigorous science applied to the history, conservation and authentication of precious stones.
Guilhem Merolle
Guilhem Merolle is a content creator with a deep passion for the history of jewelry and gemstones. For several years, he has been sharing his discoveries and research on antique jewelry through his blog and social media, where he has built an international community of enthusiasts, professionals, and curious minds.
His work has led him to collaborate with many key players in the field — including antique jewelry dealers, auction houses, jewelers, and specialized fairs and events, both in France and internationally.
To take his passion further, he founded Collectissim, a platform dedicated to the world of jewelry and gemstones, which includes a website, a YouTube channel, and an active presence on social media. In 2024, he launched Collectissim Magazine, an independent high-end publication focused on jewelry, its history, savoir-faire, gemology, and the market. With international distribution, the magazine is aimed at professionals, collectors, and anyone with a keen interest in fine jewelry.
Ronald Ringsrud
Read Profile
Ronald Ringsrud is a U.S.-born emerald expert and dealer whose career has unfolded between California and Bogotá for several decades. A chance job in the Gemological Institute of America’s warehouse introduced him to the trade; captivated, he began frequent trips to Colombia, learning the markets and the mines and developing the eye of a field buyer.
His pioneering 1983 article in Gems & Gemology on oil treatment of Colombian emeralds helped the industry discuss enhancement more openly and accurately. Returning to Bogotá as often as six times a year, he built relationships with miners and merchants, educated buyers, and pushed back against myths such as green-tinted oils. In 2013 he joined Muzo International, evaluating stones and supporting international sales as the historic mine modernized its operations. Ron also founded Clayhands, a nonprofit that trains rural youth in low-impact building methods, and his outlook is informed by a respect for nature inspired by the Kogi people.
Author of Emeralds: A Passionate Guide (2010) and The Hardness of Emerald (2025), he divides his time between the United States and Colombia, continuing to trade, write, and share his passion.
George Smith
Read Profile
George Smith is a London-born, Bogotá-based Colombian emerald dealer and founder of Alpine Green. After studies in economics and history and an early career in City finance, a 2013 trip to Colombia set him on a new path. He learned the trade from the ground up—walking the markets, spending time underground in the mines of Muzo and Chivor, and refining an eye for top-grade stones.
Early sales to a leading London jeweler confirmed the shift, and he built a niche supplying exceptional Colombian emeralds to jewelers, designers, and private collectors worldwide. Known for integrity and clear communication, he prioritizes meticulous sourcing, traceability, and fair dealing with miners, often providing mine-of-origin documentation when available.
Headquartered in Bogotá with offices in Miami and Dubai, he works across time zones and markets. On Instagram he shares field notes, mine visits, and selected stones, helping collectors make informed decisions.
Geoffray RIondet
Read Profile
Geoffray Riondet is a gemmologist (HRD, GIA, DU de gemmologie), expert for the Lyon courts, specializing in antique jewelry. He has taken part in the on-site gemmological analysis of numerous historic gems and jewelry pieces, including : Louis XIV’s “Grand Saphir” at the Muséum National d’Histoire Naturelle (2012), Charlemagne’s “Talisman” at the Palais du Tau (2016), Empress Josephine’s coronation ring at the Musée National des Châteaux de Malmaison et Bois-Préau (2016), the crown of Notre-Dame de Fourvière (2016), George Sand’s jewelry at the Musée de la vie Romantique (2017), the Majesty of Sainte Foy de Conques (2017), the Book of Hours of François Ier at the Louvre Museum (2020).
He is also renowned for his ongoing research, publishing numerous articles (over 70 to date) for magazines such as Revue de Gemmologie, Gems & Gemmology and The Journal of Gemmology. Geoffray Riondet is also the author of the book “Bijoux anciens (1800 – 1950). Découvrir, apprécier et identifier”, published by Flammarion in May 2021.
Geoffray Riondet is a professor at the Institut National de Gemmologie. He also lectures at the Université Claude Bernard Lyon 1 as part of the Diplôme Universitaire de Gemmologie.
Gérard Panczer
Read Profile
Gérard Panczer is a professor at Université Claude Bernard – Lyon 1, a researcher at the Institut Lumière–Matière, and head of DUGEM, Lyon’s university diploma in scientific gemology. A physical chemist, mineralogist and gemologist, he has championed portable spectrometry for non-invasive analysis of gemstones in cultural-heritage objects.
Working in situ, he has examined the gemstones of: Roger Caillois’s Académicien’s sword by Jean Vendôme (Musée des Confluences, Lyon); the Pépin shrine (Conques); Catherine de Medici’s pendant (BnF, Paris); Gallo-Roman jewels with rough emeralds (Lugdunum, Lyon; BnF, Paris); Honoré de Balzac’s turquoise cane (Maison de Balzac, Paris); major pieces from Adèle de Rothschild’s collection (Château d’Écouen); the Book of Hours of Francis I (Louvre, Paris); and the Talisman of Charlemagne (Reims).
All of these investigations have resulted in publications or formal institutional reports, reflecting Panczer’s commitment to rigorous science applied to the history, conservation and authentication of precious stones.
Guilhem Merolle
Read Profile
Guilhem Merolle is a content creator with a deep passion for the history of jewelry and gemstones. For several years, he has been sharing his discoveries and research on antique jewelry through his blog and social media, where he has built an international community of enthusiasts, professionals, and curious minds.
His work has led him to collaborate with many key players in the field — including antique jewelry dealers, auction houses, jewelers, and specialized fairs and events, both in France and internationally.
To take his passion further, he founded Collectissim, a platform dedicated to the world of jewelry and gemstones, which includes a website, a YouTube channel, and an active presence on social media. In 2024, he launched Collectissim Magazine, an independent high-end publication focused on jewelry, its history, savoir-faire, gemology, and the market. With international distribution, the magazine is aimed at professionals, collectors, and anyone with a keen interest in fine jewelry.