Blue Nile offers consumers only the highest quality, authentic gemstones. Our coloured gemstones undergo rigorous internal
inspections by our trained gemologists to ensure they meet our stringent quality standards.
Due to their rarity and unique visual properties, nearly all colored gemstones sold at fine jewellers, including Blue Nile,
are enhanced using various techniques. Many of these techniques have been used for centuries. Colored gemstones that have not
been enhanced are very rare and command extravagant prices.
Our white and fancy-colour diamonds are not enhanced in any way, other than normal cutting and polishing. Black diamond fashion jewellery contains natural diamonds that have been treated to create the unique black colour.
There are many methods of enhancing colored gemstones. We describe
the most common enhancements below. For more information on colored gemstone enhancements, see the American Gem Trade Association's
Gemstone Information Manual.
- Heat Treatment
The application of heat to enhance the colour and/or clarity of gemstones has been a common practice around the globe for centuries. It is part of the standard polishing and finishing process for many colored gemstones. As such, it is accepted by the jewellery industry and the American Gem Trade Association. The enhanced colour and/or clarity of heat-treated gemstones is permanent.
- Infusion
The filling of a gem material with an oil, wax, glass, resin or other material, colored or colorless, to improve appearance. This process began centuries ago by gemstone merchants who found that immersing emeralds in oil or waxes made them look clearer to the unaided eye. This practice continues today with many colored gemstones.
- Coating
The use of wax, resin or oil applied to the exterior of a porous colored gemstone to protect the natural substance, and to improve sturdiness and appearance.
- Bleaching
The application of chemicals or other elements to lighten or enhance colour consistency.
- Dyeing
The act of adding coloring agents so that they permeate a colored gemstone to enhance or alter colour.
- Irradiation
The alteration of a gemstone's colour through the use of radiation. This is often followed by a heating process. The enhanced colour of irradiated gemstones is permanent.
- New and Future Technologies
Techniques for enhancing colored gemstones, either detectable or otherwise, are continually being developed. These may be difficult, or in rare cases, impossible to detect, even for the most sophisticated laboratory. Blue Nile will continue to work with industry groups and gemmological experts who are committed to the identification and disclosure of new and future techniques in order to maintain our stringent quality standards.
While gemstones are durable, they require varying levels of care. For example, some gemstones are especially
vulnerable to household chemicals and temperature changes. Cleaning gemstones presents special challenges.
While many gemstones should be cared for by following our basic care guidelines below, please refer to our
Gemstone and Pearl Care and Enhancement Overview to understand the care requirements for your specific stone. If
you still have questions, please contact Blue Nile customer service.
| Gemstone |
Accepted Enhancements |
Gemstone Care |
Agate |
Heated or dyed to improve colour. |
Basic Gemstone Care. |
Amber |
Heated to improve colour and clarity. |
Do not use ultrasonic cleaning. Avoid sudden temperature changes, chemicals, perfume, cosmetics, and hairspray. |
Amethyst |
Heated to improve colour. |
Basic Gemstone Care. |
Apatite |
Heat |
Basic Gemstone Care. |
Aquamarine |
Heated to improve colour and clarity. |
Basic Gemstone Care. |
Black Diamond |
Heated or irradiated to alter colour. |
Basic Gemstone Care. |
Black Onyx |
Dyed. |
Basic Gemstone Care. |
Black Spinel |
None. |
Basic Gemstone Care. |
Blue Topaz |
Heated and/or irradiated to alter colour.
Thermal coated to alter colour. |
Basic Gemstone Care. |
Carnelian |
Heated to improve colour. |
Basic Gemstone Care. |
Chalcedony |
Dyed. |
Basic Gemstone Care. |
Chrome Diopside |
None |
Basic Gemstone Care. |
Citrine |
Heated to improve colour. |
Basic Gemstone Care. |
Coral |
Coated or impregnated with colour less substances to improve surface uniformity or durability.
Bleached or dyed to enhance colour. |
Basic Gemstone Care. |
Diamond |
None. |
Basic Gemstone Care. |
Emerald |
Infused to improve clarity and/or colour. |
Do not use ultrasonic cleaning. Avoid sudden temperature changes, chemicals, perfume, cosmetics, and hairspray. |
Fire Opal |
None. |
Do not use ultrasonic cleaning. Avoid sudden temperature changes, chemicals, perfume, cosmetics, and hairspray. |
Garnet |
None. |
Avoid sudden temperature changes. |
Iolite |
None. |
Do not use ultrasonic cleaning. |
Kunzite |
Heated or irradiated to improve colour |
Do not use ultrasonice cleaning. Avoid direct sunlight. |
Labradorite |
None. |
Basic Gemstone Care. |
Lapis |
Dyed. |
Do not use ultrasonic cleaning. Avoid sudden temperature changes, chemicals, perfume, cosmetics, and hairspray. |
Moonstone |
None. |
Basic Gemstone Care. |
Morganite |
Heated to improve colour and clarity. |
Basic Gemstone Care. |
Opal |
Coated to alter surface consistency and durability. |
Do not use ultrasonic cleaning. Avoid sudden temperature changes, chemicals, perfume, cosmetics, and hairspray. |
Pearl (natural and cultured) |
Bleached, dyed, polished and coated. |
Do not use ultrasonic cleaning. Avoid sudden temperature changes, chemicals, perfume, cosmetics, and hairspray. For more information, visit Pearl Education. |
Peridot |
None. |
Basic Gemstone Care. |
Prehnite |
None |
Basic Gemstone Care. |
Quartz |
Green/Lemon: Irradiated to improve colour. Smokey: Heated to improve colour. Blue: Dyed. Rutilated/Rose/white: None. |
Basic Gemstone Care. |
Ruby |
Heated and/or infused to improve colour and clarity. |
Basic Gemstone Care. |
Sapphire |
Heated and/or infused to improve colour and clarity. |
Basic Gemstone Care. |
Spinel |
None |
Basic Gemstone Care. |
Tanzanite |
Heated to alter colour and clarity. Infused to alter colour and clarity. |
Do not use ultrasonic cleaning and sudden temperature changes. |
Tourmaline |
Irradiated to improve colour. |
Do not use ultrasonic cleaning and sudden temperature changes. |
Turquoise |
Coated or impregnated with colour less substances to improve surface uniformity or durability. |
Do not use ultrasonic cleaning. Avoid chemicals, perfume, cosmetics, and hairspray. |
White Agate |
None. |
Basic Gemstone Care. |
White Topaz |
None. |
Basic Gemstone Care. |