Gemlab - Heat Treating Ruby and Sapphire

HEAT TREATING RUBY & SAPPHIRE

Among the various types of gem treatments practiced today, the heat treatment of ruby and sapphire is the most common and most important. Rubies and sapphires heated under certain conditions in order to improve their color and/or clarity, thus increase their value. The results after the heating vary widely and depending upon the type of material, ratio/type of the color-bearing impurities, heat treatment technology, heating method applied, equipment used and other parameters.

For those individuals wishing to serious study the heat treatment of ruby & sapphire may attend our special 6-day "on-hand" practical course offered periodically several times per year in our heat treatment laboratory premised in Bangkok. Details click here.

Those wishing to read more about he subject can buy our book "The Heat Treatment of Ruby & Sapphire- SECOND EDITION". Click here for details.

The most common heat-treating processes applied to ruby-sapphire as defined by Ted Themelis using his heating technology and methodology developed over the last 30 years as described as follows:

Some heat-treating processes of ruby-sapphire as defined by Ted Themelis
#	PROCESS	COMMENTS	BEFORE HEATING	AFTER HEATING
3	FRACTURE FILLING	Surface-reaching fissures/cracks and cavities may be filled with additives to improve their clarity, luster and appearance
4	DEVELOP ORANGE	Dark/purplish red rubies may turn orange to golden-orange, specially when beryllium is used as additive in the process.
9	INTENSIFY YELLOW, DEVELOP ORANGE	Pale yellow sapphires may be intensified to deeper yellow, or may turn orange/yellow and other colors. When beryllium and other additives are used the color improvement is dramatic.
10	DEVELOP BLUE	Milky-silky (geuda) or partially blue ("ottu", "ural") and other types of corundums may turn to near-uniform blue.
18	SURFACE/SUBSURFACE COLOR DIFFUSION	Lab prepared additives heated with selected natural, synthetic, or previously treated corundums may produce near-uniform blue, pink, orange, orange-pink coloration. The color is confined at/near the surface/subsurface of the stone.

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