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These highlly acclaimed seminars are conducred by Ted Themelis periodically upon invitation by gemological associations, alumin, trade organizations and industry groups aoutnd the world.. more

Topics of gemological interest are discussed: microscopes, gem treating technology-equipment, detection of gem treatments, etc.

STATE-OF-ART GEMSTONE MUFFLE TUBE FURNACES 1200oC to 1720oC NEW MODELS Our affiliate web site provides all information on our NEW muffle models M50P-1720, M80P-1720, V80-1200, BV50-1200-mini combo and our High Pressure- Low-Temperature reactor for treating emeralds model HPLT-300 and related equipment we fabricate in our workshop in Bangkok Click for details www.gemstonetreatments.com
M80P-1720	M50P-1720	V80-1200	BV50-1200	HPLT-100D

NEW PUBLICATION (released June 2025): MONOGRAPHS No.1-7 THE HEAT TREATMENT

by Ted Themelis
Total 7 monographis+slipcase
530 pp. full color
Over 1010 color photos
Price:USD350 postpaid
Published: June 2025

These monographs are written based on the fundamental structure of the previous editions of The Heat Treatment of Ruby- Sapphire, written and published by the same author in 1992, 2012, and 2019. This newest edition (June .2025) is presented in the form of monographs, aiming to provide the tools for understanding the heat treatment of ruby-sapphire, learning how to think alternatively, and producing new ideas that will ultimately formulate new models and exciting new inspirations.

MONO No.1. An intrroduction to the Heat Treatment of Ruby-Sapphire
MONO No.2. First Principles in Heating Ruby-Sapphire
MONO No.3. The Effect of Heat on Attributes of Ruby-Sapphire
MONO No.4. The Effect on Inclusions of Ruby-Sapphire
MONO No.5. Heat Treatment Parameters of Ruby-Sapphire
MONO No.6. Methodology of Heat Treating Ruby-Sapphire
MONO No.7. Equipment for Heat Treating Ruby-Sapphire

RECENT ARTICLES TO HEAT TREATMENT OF RUBY & SAPPHIRE
Select any article summary below to open the full paper.

Foundations of the Ruby–Sapphire Heat Treatment: The First Question
In July 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, addressed the first question in applying the scientific method and modern furnace technology to ruby and sapphire heat treatment. The paper identifies atmosphere, pressure, temperature, and additives as variables that must be measured and controlled to reproduce treatment conditions consistently, contrasting this approach with methods that depend on imprecise equipment.

The Omega (Ω) M50-1700 Furnace—Architecture and Gas Dynamics in Heating Ruby-Sapphire
In April 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, documented the design and engineering of the Omega (Ω) M50-1700 furnace for ruby and sapphire heat treatment. Its vertical alumina muffle separates the gemstones and treatment gases from the heating elements. The furnace maintains temperatures up to 1,700°C while treatment gases pass through the chamber in a controlled atmosphere.

Oxidative Color Modification of Dark Blue Mambilla Plateau Sapphire: A Defect-Kinetic Interpretation
In March 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, reported results from controlled oxidation heat treatments of dark blue sapphires from the Mambilla Plateau in Nigeria. The paper documents the experimental parameters used to reduce their oversaturated blue appearance.

Oxidative Color Modification of Ruby: A Defect Kinetics Model for Reducing the Purplish Tinge
In March 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, described experiments using filtered dry air in a precision electric furnace below 1,200°C to reduce the purple tint in selected rubies. The paper reports that the treatment reduced the blue component responsible for the purple tint while preserving the gemstones’ natural inclusions.

Defect Corridor Along the Compensated Furnace Trajectory (CFT) in Sapphire Heat Treatment
In March 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, examined how adjusted LPG-oxygen settings in a Lakmini furnace affect sapphire color. Experiments at 1,650°C identified a narrow operating range that promotes blue coloration while avoiding destructive changes within the host crystal.

High-Temperature Quasi-Isochoric Gas-Phase Reduction (HT-QIGPR): Hydrogen Fugacity-Driven Electronic Reduction in α-Alumina
In March 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, examined the proposed chemical mechanism behind his confined-gas sapphire treatment. The paper suggests that hydrogen inside a custom electric furnace supplies the electron needed to change Fe³⁺ to Fe²⁺, helping produce uniform blue color without mechanical pressure or surface damage.

HT-QIGPR: Operational Interpretation for Reducing Sapphire Treatment
In March 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, described how a specially designed electric furnace with a dedicated flange assembly creates a confined, hydrogen-rich atmosphere for sapphire treatment. The paper proposes that hydrogen changes the state of iron within the corundum, contributing to blue coloration and producing cleaner, more uniform results without mechanical pressure.

Compensated Furnace Trajectory Normalization for Redox Control in LPG–O₂ Combustion Sapphire Heat Treatment
In February 2026, independent researcher Ted Themelis of Gemlab in Bangkok, Thailand, tested a method for improving redox control in manual LPG-oxygen furnaces used to heat sapphires. Across three heating runs at 1,650°C, the method adjusted for fuel, temperature, flowmeter, and gemstone variations, producing more consistent blue color.

BLUE SAPPHIRE BLUEPRINT: The Etiology of Mechanical and Atmospheric Failure: A Thermodynamic and Engineering Analysis in Gas-Oxy Combustion Furnaces
In February 2026, independent researcher Ted Themelis examined why geuda sapphires treated in Sri Lankan Lakmini gas-oxygen furnaces can produce inconsistent blue color. Drawing on four decades of laboratory and field experience, the paper explains how gemstone chemistry, furnace atmosphere, fuel flow, and mechanical wear must remain within a narrow operating range for reliable results.

Reconciling Fickian Diffusion Theory with Non-Fickian Diffusion Reality in Heat Treating Corundum
In December 2025, independent researcher Ted Themelis compared standard diffusion theory with results from more than 3,000 practical corundum heat-treatment experiments. Standard theory suggests that color-changing diffusion should take years, yet practical ruby and sapphire treatments achieve it within hours. The paper explains how crystal defects and surfaces may allow this process to happen much faster.

The Heat Treatment of Ruby & Sapphire: Experiments & Observations, 3rd edn., Vol. 1: Attributes of Ruby-Sapphire and Related Heating Technology
In 2018, Dr. Lore Kiefert of Gübelin Gem Lab in Lucerne, Switzerland, reviewed Ted Themelis’s third-edition volume on ruby and sapphire heat treatment. He praised it as a thorough, experience-based guide containing practical information difficult to find elsewhere. Built on decades of original laboratory experiments, the book stands as the most comprehensive hands-on reference devoted to the heat treatment of ruby and sapphire.