About Us


Established in Bangkok in 2017, the Institute of Gem Trading offers gemological courses based on decades of experience in mining, cutting, and gem trading. Through our modular short courses, you will learn the skills of the modern professional field gemologists such as grading rough colored gemstones, cutting and recutting gems in order to maximize values, as well as mastering the trade secrets of the colored gemstones market. With a hands-on approach, students will learn through lectures, videos, interactive demonstrations, sample specimens, workshops, field trips, and seminars by industry leaders.

Meet The Team

Our team and founders are passionate communicators with years of first-hand experience in the gem trade.

Justin K Prim

Faceting Instructor
Justin K Prim is an American gem cutter and author. He has been cutting gemstones since 2013 and has trained as a lapidary in the United States, Thailand, Sri Lanka, and Switzerland.To support his work as a gem cutter, he has attended gemology programs at GIA and AIGS. He has travelled around the world to various gem producing regions to learn more about rough, and has visited mines in Thailand, Cambodia, Europe, and the Americas.

Before joining IGT, Justin was teaching Gemology courses at AIGS Bangkok.He is currently working on a book about the regional histories of colored gemstone faceting and regularly travels around the world researching lapidary history. Aside from teaching and writing, Justin also gives talks and presentations about faceting and faceting history.

Alex Teoh

Jewelry CAD Instructor
Alex Teoh is a Jewelry CAD Designer with GIA Graduate Gemologist background. Teoh started his 3D career in Vancouver, Canada, working in the game design industry for 10 years. In 2012, he attended GIA in Bangkok and since then he started to design and produce his own jewelry with 3D CAD software and his prior 3D knowledge. In 2014, he became the head of the jewelry prototype department for an international jewelry factory. He formed a jewelry CAD team and for 2 years they worked to create high quality jewelry prototypes as well as increasing production efficiency.

Teoh wishes to share his knowledge and experience of jewelry CAD design and creation, to help reduce the learning curve of 3D CAD design while increasing the quality of jewelry production for his students.

Sarath Chandrasiri

Faceting Instructor
Sarath is a master gemcutter from Sri Lanka with over 30 years of experience. For the last 17 years he has been the head faceter for the Yavorskyy company was part of the original gem cutting team for Yavorskyy’s cutting factory in the early 1990’s.

Sarath regularly travels between Bangkok and Sri Lanka, doing work for clients all over the world. His specialty is faceting large stones, having cut everything from sapphire to tanzanite to tourmalines and everything in between.
Sarath has worked in all parts of the gem cutting industry. Over the years, he has worked with several factories to produce his own cutting machines and his own laps which he has sold in Sri Lanka and also imported to Bangkok. Sarath brings many decades of cutting mastery to the IGT cutting class and hopes to impart his wisdom onto our students.

Karim Guerchouche

Karim has been working in the gemstone industry since 1988. He started a cutting factory in Chanthaburi that specializes in Swiss-Quality precision gem cutting for the watch industry. His area of expertise is in the treatment of various types of gemstones. Through various collaborations with major mining companies and gem labs, along with years of experimenting, Karim has developed his own heat treatment techniques for Ruby, Sapphire, Spinel, and more.

Karim has bought gems in many countries around the world, including Burma, India, Pakistan, Madagascar, Mozambique, Tanzania and he’s now a Gemfields Authorised auction Partner.

Noah Severs

Noah Severs is an entrepreneur and innovator. Formerly Noah founded American Gemstone Group, a technology centric jewellery manufacturing organization which produced jewelry for leading brands worldwide and employed over a hundred people.

Philippe Ressigeac

Philippe’s main area of expertise is in rough gemstones. By living in key mining and manufacturing hubs such as Burma and Thailand, and travelling extensively in various countries such as Vietnam, Madagascar, Mozambique, and Burma, collecting specimens, he has acquired a vast knowledge of gem cutting and grading.

In Madagascar, he worked for 3 years with a Swiss partner in Sapphire mining and cutting and also co-founded a jewelery retail business in the country. In Mozambique, he worked for 3 years with Gemfields at Montepuez Ruby Mine, where he co-developed their proprietary Ruby grading system and Ruby auctions. After leaving Gemfields, he acted as a consultant and created the Gemfields Masterclass educational program, which has run worldwide since September 2016 with hundreds of students in attendance. Philippe is a Gemfields Authorised auction Partner.
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