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How to Heat Sapphire

Sapphires in their natural state are totally clear or have a pale, faint color. Treating sapphires with heat dates back to ancient Egypt, when Egyptians heated the stones to bring out the subtle colors. Most sapphires sold on the market today have received some form of heat treatment, which is a more intense heating process from centuries ago. Starting in the 19th century, when high temperature ovens became available, gemologists began heating sapphires at a high temperature to bring out the darker tones of the stone, such as the deep blue most people associate with sapphires.

Things You'll Need

Natural sapphire
Furnace or high temperature oven

Instructions

- 1
  Select the sapphire you want to treat with heat.
- 2
  Choose the temperature you want to use to heat the sapphire. According to The Natural Sapphire Company, you can heat the sapphires at temperatures as low as 400 degrees Celsius (752 degrees Fahrenheit) and as high as 1700 degrees Celsius (3092 degrees Fahrenheit). The lower range will burn off secondary colors the gem may have, while the higher temperature will increase the color and clarity of the gem. Once you have selected the temperature, heat the sapphires in the furnace or high temperature oven.
- 3
  Allow the sapphires to cool until you can sort them. Sort and separate the sapphires that have achieved satisfactory color. According to the website Gem Mountain Sapphire Mine, 15 to 20 percent of the gems will turn yellow or orange. This first stage burn is referred to as the "Fancy Burn." Any gems that did not achieve the desired color and clarity in the first stage are put back in the furnace for a second burn.
- 4
  Reheat the remaining gems for a second burn. Gem Mountain Sapphire Mine refers to this stage as the "Blue Burn." Most sapphires will turn a bright blue or teal after this heat second treatment.

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