Jewel School

All About Gemstones

Most natural colored gemstones are treated or enhanced to intensify color, diminish imperfections or improve durability. Explained below are the most commonly used and accepted treatments for different types:

Emeralds

Emeralds range in color from light to dark green. Oiling is an ancient process used to enhance the clarity of emeralds. Oil is applied to the emerald and seeps into the fissures, which reach the stone's surface. Aside from improving clarity, this process may prevent brittleness. Oiling is generally not permanent and may need to be reapplied every few years. Special care is required for cleaning, repairing or mounting oiled stones.

Rubies

Rubies range in color from brownish red to light red. Heat treatments are applied to rubies to maximize their shade of red and/or improve the stones clarity. Rubies are second to diamond on a scale of hardness and are very durable. Rubies can be maintained with mild cleaning.

Sapphires

Sapphires are available in many colors; they are the most important and versatile of all the gemstones. Heat treatments have become common in recent years, as a way of improving color. The attribute of hardness of the sapphire makes it a perfect choice for jewelry that needs to stand up to everyday wear. Sapphires also require mild cleaning.

Other Stones

Heating is a widely accepted enhancement process used on amber, aquamarine, amethyst, citrine, tiger-eye, tanzanite, topaz and tourmaline. This treatment improves the transparency and/or color of the stone. Since heating is generally permanent, heated stones do not require special care.

Diffusion is another method occasionally used particularly on blue sapphires. During treatment, a colorless sapphire is coated with a titanium and oxide compound and exposed to heat. This enhances and/or changes the color of the stone and does not generally require special treatment.

Irradiation is often used with blue topaz. The stone is irradiated brown and then heated to produce the blue color. Irradiated stones do not require special care.

If you have any questions, or would like information on other treatments used for colored gemstones, ask your Morgan Jewelers Sales Associate.

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