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Applications
Gemlab furnaces have been engineered for heat-treating rubies and sapphires at temperatures between 1200oC and 1800oC. Most heat-treatment applications for ruby-sapphire require temperatures up to 1700oC, fewer to 1800oC. Gemlab F-series furnaces utilize MoSi2 elements, thus heating processes below 1200oC are not recommended due to oxidation nature of the MoSi2 heating elements.
The heat treatment of ruby-sapphire is based upon the knowledge and experience of the heat treater to develop the "know-how" technology. Gemlab F-series furnaces merely perform the heat treatment processes as instructed by the heat treater.
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| Samples of heating processes performed using Gemlab F-series furnaces |
HEATING
PROCESS |
FURNACE
MODELS |
IMAGE |
| REDUCE BLUISH-PURPLISH TINGE
IN RUBY-PINK SAPPHIRE |
MB50, M50, M76 |
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| REDUCE BLUE PATCH -STREAK IN RUBY-PINK |
MB50, M50, M76 |
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| DEVELOPMENT OF ORANGE, PAD-LIKE SAPPHIRE |
MB50, M50, M76 |
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| ALTERING LIGHT YELLOW SAPPHIRE |
MB50, M50, M76 |
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| DEVELOPMENT OF BLUE FROM "GEUDA",
"OTTU" |
M50, M76 |
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| DEVELOPMENT OF BLUE FROM "OTTU"
SAPPHIRE |
M50, M76 |
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| DEVELOPMENT OF BLUE FROM
GREEN-BLUE |
M50, M76 |
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| DEVELOPMENT OF LILAC, COLOR CHANGE |
M50, M76 |
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| REDUCING ASTERISM-SILK IN RUBY-SAPPHIRE |
M50, M76 |
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| DEVELOPMENT OF BLUE FROM GREYISH STAR
|
MB50, M50, M76 |
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| DEVELOPMENT OF SURFACE COLOR |
MB50, M50, M76 |
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| DEVELOPMENT OF SURFACE ASTERISM-SILK |
MB50, M50, M76 |
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LEAD-BASED FRACTURE
FILLING PROCESS |
MB50, M50, M76 |
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| BORAX-BASED FRACTURE FILLING PROCESS |
MB50, M50, M76 |
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| BERYLLIUM PROCESS OF RUBY-SAPPHIRE |
MB0, M50, M76 |
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| HEATING PROCESSES OF SYNTHETIC CORUNDUM |
MB50, M50, M76 |
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| Notes |
| In some cases, heating is preformed first using a combustion furnace, then heating using any model of Gemlab furnace. |
| Fast cooling to prevent re-crystallization of silk requires elevator (Models M50, M76) |
| Lead filling process is suitable only if heating above 1200oC |
| Muffle tube is strongly recommended if additives are used in the Pb-based, borax-based and beryllium)the processes |
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