Definitions and gemstone enhancement codes
Enhancement is defined as any process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, or availability of a gemstone.
Enhancement at a glance
Most natural coloured gemstones are treated or enhanced to intensify the
colour, diminish imperfections or improve durability. Perhaps the most
basic enhancement, is the faceting and polishing of a gemstone in order to
enhance its beauty and wearability. This enhancement, of course, does not
have to be disclosed because the gem´s outward appearance makes it
obvious that the process has taken place.
Other treatments may not be so obvious or quite so durable. Depending upon
the material, some gems might be subjected to heating, irradiation, diffusion,
filling of surface-reaching fractures with foreign compounds , bleaching, or dyeing.
Commonly used and accepted treatments for different types of coloured
stone are: Oiling, Heating (also known as a Burning") and Diffusion.
For example: many corundums have been heated to enhance the color and this treatment is generally excepted in the trade.
Oiling Method
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.
Heating Method
Heating is a widely accepted enhancement process used on rubies, sapphires,
amber, aquamarine, amethyst, citrine, tiger eye, tanzanite, topaz and tourmaline.
This treatment improves the transparency and/or colour of the stone. Much corundum
has been heated to enhance the colour. This treatment is generally excepted in
the trade. Some of our tourmalines and blue zircons have also been heated and the
resulting colour is permanent. Since heating is generally permanent, heated stones do
not require special care.
The new method for producing yellow and orange sapphires is a natural outgrowth
of the traditional heating methods called "new heat treatment". Rough sapphire especially from Tanzania, Sri Lanka, and
Madagascar is usually found associated with spinel, zircon, tourmaline,
chrysoberyl and other gemstones. The mine run material is always very difficult
and time consuming to separate before cooking. Thai burners noticed that some
of these other gemstones could actually influence the burn. More specifically, it
was discovered that the introduction of small quantities of natural chrysoberyl in
the crucible would increase the preponderance of yellow and orange colors in the
sapphires being burned.
Scientists discovered that beryllium from the chrysoberyl was being diffused
in extremely small and barely measurable quantities and that this was a critical
aspect of the chemical reaction which affected the coloration in many of the
sapphires. Whether beryllium is acting as a catalyst or not is still the subject
of debate. The treatment can produce complete and total color penetration and is
undetectable by conventional non-destructive gemological testing methods. Although
new laser ablation technologies can detect and measure beryllium and other trace
elements, these determinations are too expensive to be used for general gemological
purposes.
Diffusion Method
Diffusion is method occasionally used particularly on blue sapphires. During
treatment, a colourless sapphire is coated with a titanium and oxide compound and
exposed to heat. This enhances and/or changes the colour 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 colour. Irradiated
stones do not require special care.
Enhancement Codes
The table below sets forth proper methods to comply with the FTC Guides.
With the exception of the normal fashioning (cutting and polishing) of gemstone,
it is the seller´s responsibility at the time of the sale to provide all
information pertinent to the enhancement and alteration of a natural gemstone.
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| A (None) |
Indicates either a gemstone that is not currently known to be enhanced or one that is so rarely enhanced that to give it an "E" symbol would mislead the public. Example: Amethyst is rarely known to be treated. |
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| Acid Wash |
The acid used for removing the black spots and dust from the stone's surface. |
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| H |
Indicates the stone has been heated to effect desired alteration of color, clarity, and/or phenomena.
Example: Sapphire is commonly enhanced in this manner.
Example: Citrine is commonly enhanced in this manner. |
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| T |
The treatment is a heat diffusion process in which an ion foreign to the original chemical composition of the sapphire is deliberately diffused into the sapphire. The color completely penetrates the stone. This treatment is permanent. |
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| Treated |
Treatment of gemstones to is done primarily to remove local color concentration and to improve the depth of color. |
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Enhancement should be always disclosed. Customers can decide what they want but
they should not be mislead and should be informed of the existence of any treatments or enhancements when making a purchase. The information allows them to make their own careful and informed choices.
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