Live Online Seminar

Low Temperature Heat Treatment Seminar

A blow pipe burner sitting on the ground heat treating a pink sapphire over an open flame.
A blow pipe burner from Ratnapura (Sri Lanka) was working on heat treating a pink sapphire. This treatment is primitive but very effective to use low heat to remove the blue component in pink sapphire to make its color appearance more attractive. However, positively identifying if colored gems are treated this way is challenging for gemologists.

Low temperature heat treatment of certain kinds of corundum has been a major concern to the industry in the past several years. This two-hour seminar will focus on how GIA Research develops more reliable ways to identify low temperature-heated stones from stones that have not been treated.

Participants will be guided by GIA researchers with expert knowledge of low temperature heat treatment of corundum and the processes used by GIA’s laboratories. Learn from illustrations, images, video and live demonstrations that let you see exactly what our experts see as they examine some of the very samples used in this research and learn to separate the sometimes subtle changes in inclusions that happen at these temperatures. Participants will have the opportunity to interact with the instructor during the seminar, and will receive digital reference material.

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The number of attendees will be limited to ensure the best experience for attendees.

Topics include:


  • Low temperature heat treatment and its application on corundum

  • The challenges and limitations involved with conclusively identifying treated corundum


Before and after the low heat treatment of a piece of Mozambique ruby. The change of color appearance is very subtle but the treatment definitely reduces blue color component’s contribution to the overall appearance.


Each online seminar is two hours.

New dates may be added throughout the year.

  • April 21, 2021; 10 a.m. to 12 p.m. (Pacific Time); Researcher: Wim Vertriest
  • May 22, 2021; 10 a.m. to 12 p.m. ICT (Bangkok) / May 21, 2021; 8 p.m. – 10 p.m. (Pacific Time)
  • July 16, 2021: 10 a.m. to 12 p.m. (Pacific Time)

This live seminar will be delivered through an online learning platform.


$195 USD (GIA Alumni receive a 10% discount)


Please complete the online registration form. You will be provided information about how to access the platform after your registration is confirmed.

GIA’s continuing education offerings are considered avocational or recreational in nature and are not intended to prepare individuals for entry-level employment. They are non-credit bearing and do not lead to a GIA academic credential. They are not eligible for state or federal student financial aid programs and do not fall under the approval of the Accrediting Commission of Career Schools and Colleges (ACCSC) or the Distance Education Accrediting Commission (DEAC).

Dates, course content and instructors are subject to change.