A lot of treatments are carried out whilst the gem is in the raw crystal stage and it is often impossible to be certain what enhancements have been made to a particular gem. Our chart below highlights the most common treatments that certain gemstones undergo.
It is occasionally the case that even in one design, treatments may vary. For example, in a collection of fifty tanzanite rings, whilst the majority will have been heat treated, several pieces may not have been. Enhancements often have an impact on the value of precious stones, with the highest prices paid for natural gems of fine quality that have not been enhanced in any way beyond ordinary cutting and polishing.
Enhancement Overview
- Indology only sells genuine gemstones, many of which have been enhanced.
- For most gems today, enhancements are commonplace.
- The market place sets the values of both natural and enhanced gems.
- Since certain enhancements are undetectable or difficult to detect, assume that all items are enhanced unless it is stated from gemmological evidence otherwise or the item is a type for which enhancements are not typically used.
Enhancement Codes
The following chart explains the enhancements and treatment codes that you will see on our website and TV broadcast. They are derived from industry standard codes which we have amended for further clarification.
N = Natural (No enhancement)
Gems that are, according to best available information, untreated.
C = Coating
Enhancement by the application of an artificial layer to the surface.
H = Heat only
Enhancement via heat only.
B = Bleaching
Enhancement by heat, light, and/or chemical agents to lighten or remove colour.
U = Diffusion
Enhancement by the diffusion of foreign elements into the crystal lattice of a gemstone. Example: Beryllium-diffusion.
O = Oiling
Enhancement by bathing the gemstone in an oil to enhance the lustre and clarity of a gemstone.
HP = Heat & Pressure
Enhancement via extreme heat and pressure. Also referred to in the industry as HPHT (High Pressure High Temperature)
R = Reconstruction
Enhancement by use of heat, pressure, and/or solvents to fuse small pieces of a gem together into a larger whole. Often used in conjuction with a dye.
F = Filling
Enhancement by filling a gemstone’s cracks and crevices with a colourless substance. Fillers include, but are not limited to, glass, plastic, resin, wax, and oil.
I = Impregnation
Enhancement by melted wax or plastic forming a layer over the surface of a gemstone to improve amongest other things lustre.
FD – Filling & Dye
Enhancement by filling cracks and crevices with a coloured substance. Fillers include but are not limited to, glass, plastic, and resin.
A = Assembled
Enhancement by assembling other substances over or under a gemstone to improve durability and size.
D = Dyeing
Enhancement by the introduction of a colouring agent into a porous gemstone.
S = Smoking
Enhancement by smoking a gemstone and replacing its water content with carbon. Sometimes the smoke can be dyed.
IR = Irradiation
Enhancement of colour via the use of neutrons, gamma, ultraviolet, and/or electron bombardment.
| Gemstone | Enhancement | Prevelance | Purpose | Durability / Stability | Detection | Care & Cleaning |
|---|---|---|---|---|---|---|
| Abalone | No Enchancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Agate | No Enhancement (N) e.g, dendritic agate | |||||
| Dyeing (D) e.g, pink agate | Common | To enhance or introduce colour | Good | Detectable by a qualified Gemmologist without use of sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Alexandrite | No Enhancement (N) | |||||
| Amber | Heating | Common | To enchance colour and creat sun spangles | Good | Detectable by a qualified Gemmologist without use of sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Amethyst | No Enhancement (N) e.g, many of our Zambian, Kalomo and African Amethyst are untreated | Occasionally | ||||
| Heated (H) e.g, most of our Brazilian amethyst is heated | Common | To enhance colour | Excellent | Not detectable | No specific care required, see above for more detailed information on jewellery care | |
| Ametrine | No Enhancement (N) | Not detectable | No specific care required, see above for more detailed information on jewellery care | |||
| Ammolite | Assembled (A) | Routien | To protect the thin layer of ammolite | Excellent | Detectable by a qualified Gemmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Andesine | Diffused (U) | Common | To produce colour | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Apatite | No Enhancement (N) e.g, all our green apatites | As apatite has a low hardress rating be careful when wearing the stone | ||||
| Heated (H) e.g, blue apatites | Routine | To enhance colour | Good | Detectable only with an internationally accredited laboratory | As apatite has a low hardress rating be careful when wearing the stone | |
| Aquamarine | Heated (H) | Routine | To remove yellow and green overtones, resulting in more a pure blue colour | Very good | Not detectable | No specific care required, see above for more detailed information on jewellery care |
| Chalcedony | Dyeing(D) | Common | To produce a variety of different colours | Good | Detectable by a qualified Gemmologist without using sophisticated equipment – often assumed dyed due to unnatural colour | No specific care required, see above for more detailed information on jewellery care |
| Charoite | No Enhancement (N) | |||||
| Impregnation (I) | Common | To improve lustre | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Citrine | No Enhancement (N), e.g, Madeira Citrine | Only Madeira cirtine is untreated | ||||
| Heated (H) | Routine | To turn amethyst into Citrine | Excellent | Not detectable | No specific care required, see above for more detailed information on jewellery care | |
| Danburite | No Enhancement (N) | |||||
| Diamonds (White) | No Enhancement (N) | Routine | No specific care required, see above for more detailed information on jewellery care | |||
| Diamonds (Cognac, Brown or Champagne) | No Enhancement (N) | Routine | No specific care required, see above for more detailed information on jewellery care | |||
| Heated (H) | Occasionally | To enhance colour | Excellent | Detectable only with an internationally accredited laboratory | No specific care required, see above for more detailed information on jewellery care | |
| Diamonds (Red, Black, Green, Yellow, Blue) | Irradiated (IR) | Routine | To enhance colour | Very good | Detectable only with an internationally accredited laboratory | No specific care required, see above for more detailed information on jewellery care |
| Diaspore | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Diopside | No Enhancement (N) including star diopside | No specific care required, see above for more detailed information on jewellery care | ||||
| Emerald | No Enhancement (N) | Rare | ||||
| Oiled (O) e.g, our Zambian emerald is normally oiled | Routine | To enhance the clarity and lustre | Fair | Detectable by a qualified Gemmologist without using sophisticated equipment | Can easily be reoiled by customer. Avoid ultrasonic cleaners | |
| Filling (F) e.g, our Columbian emerald is normally filled | Common | to enhance clarity and lustre | Fair | Detectable by a qualified Gemmologist without using sophisticated equipment | May need professionally re-treating every so often. Avoid ultrasonic cleaners | |
| Fluorite | No Enhancement (N), e.g, our multi coloured fluorites in strands | As fluorite is low on the hardness scale, handle with care | ||||
| Irradiation (IR) | Common | To improve colour | Good | Detectable only with an internationally accredited laboratory | As fluorite is low on the hardness scale, handle with care | |
| Garnet | No Enhancement (N) e.g, all garnets exepct demantoid | No specific care required, see above for more detailed information on jewellery care | ||||
| Heating (H) only demantoid and is only very low heat | Rarely | To enhance colour | Excellent | Detectable only with an interntionally accredited laboratory | No specific care required, see above for more detailed information on jewellery care | |
| Goshenite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Heliodor | Irradiated (IR) | Common | To alter colour | Good | Detectable only with an internationally accredited laboratory | No specific care required, see above for more detailed information on jewellery care |
| Howlite | Dyeing(D) | Occasionally | To alter colour | Good | Detectable by a qualified Gemmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Impregnated (I) | Common | To improve lustre | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Iolite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Kunzite | irradiation (IR) | Routine | To enhance colour | Fair | Detectable only with an internationally accrediated labratory | Avoid exposure to strong light and high heat |
| Kyanite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Labradorite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Lapis Lazuli | Dyeing (D) | Common | To improve colour and remove white calcite inclusions | Very Good | Detectable by a qualified Gemmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Malachite | Impregnated (I) | Common | To improve lustre | Very Good | Detectable by a qualified Gemmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Moldavite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Moonstone | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Morganite | Heating (H) | Common | To drive out orange colours, and produce a purer pink colour | Very good | Detectable only with an internationally accrediated laboratory | Avoid extreme temperature and sudden temperature change |
| Mother of Pearl | Dyeing (D) | Common | To alter colour | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Bleaching (B) | Rare | To remove colour | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Opal | No Enhancement (N) e.g, Welo opal and Australian opal | Common | Avoid heat as it can evaporate opal’s water content resulting in crazing | |||
| Smoking e.g, black opals | Rare, only black opals | To create dark background colour and enhance play of colour | Fair | Detectable by a qualified Gemmologist using sophisticated equipment | Avoid heat as it can evaporate opal’s water content resulting in crazing | |
| Paua Shell | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Cultured Pearl | Bleaching (B), e.g, white pearls | Routine | To remove colour and produce a purer white colour | Very good | Not detectable but assumed treatment has taken place | |
| Dyeing(D), e.g, any other colour than white | Common | To produce colours | Very good | Detectable by a qualified Gemmologist using sophisticated equipment | ||
| Peridot | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Petalite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Quartz | No Enhancement (N) e.g, white quartz and rutile quartz | Common | No specific care required, see above for more detailed information on jewellery care | |||
| Coating (C) e.g, mystic quartz | Occasionally | To produce colour | Fair | Detectable by a qualified Gemmologist without using sophisticated equipment | Avoid scratching the pavilion as the coating can scratch | |
| Irradiated (IR) e.g, smokey quartz and blueberry quartz | Occassionally | To enhance colour | Good | Not detectable | No specific care required, see above for more detailed information on jewellery care | |
| Dyeing(D) e.g, blue quartz | Rare | To produce colour, must be quench crackled first to produce fractures | Good | Detectable by a qualified Gemmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Heated (H) | Common | To enhance colour | Very Good | Not detectable | No specific care required, see above for more detailed information on jewellery care | |
| Rhodocrosite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Ruby | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Heated (H) | Routine | To enhance colour | Very Good | Detectable by a qualified Gemmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Diffused (U) | Common | To enhance colour | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Filled (F) | Common | To improve clarity and colour | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Sapphire | No Enhancement (N) | Rare | No specific care required, see above for more detailed information on jewellery care | |||
| Heated (H) | Routine | To enhance colour | Very Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Diffused (U) | Common | To enhance colour with beryllium | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Filled (F) | Rare | To improve colour and clarity | Good | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Dyeing(D) | Rare | To enhance colour | Fair | Detectable by a qualified Gemmologist using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Scapolite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Sillimanite | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Snowflake Obsidian | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Sodalite | No Enhancement (N) | Common | No specific care required, see above for more detailed information on jewellery care | |||
| Dyeing(D) | Occasionally | To enhance colour | Very Good | Detectable by a qualified Gemmologist using sophisticated equipment | Avoid ultrasonic cleaners and steam cleaners as dye fades. | |
| Sphene | No Enhancement (N) | |||||
| Heated (H) | Rare | To create a red or orange colour | Good | Detectable by a qualified Gemmology using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Spinel | No Enhancement (N) | |||||
| Heated (H) | Rare | To improve colour and clarity | Excellent | Detectable only with an internationally accredited laboratory | No specific care required, see above for more detailed information on jewellery care | |
| Sunstone | No Enhancement (N) | No specific care required, see above for more detailed information on jewellery care | ||||
| Tanzanite | Heated (H) | Routine | To enchance colour | Excellent | Not detectable but assumed due to prevalance | No specific care required, see above for more detailed information on jewellery care |
| Topaz | No Enhancement (N) e.g, imperial topaz and white topaz | Occasionally | No specific care required, see above for more detailed information on jewellery care | |||
| Heated (H) | Rare | To enhance colour | Excellent | Not detectable | No specific care required, see above for more detailed information on jewellery care | |
| irradiated (IR) e.g, blue topaz | Common | To enhance colour | Excellent | Detectable only with an internationally accredited laboratory | No specific care required, see above for more detailed information on jewellery care | |
| Coating (C) e.g, mystic topaz | Common | To produce colour in colourless topaz | Fair | Detectable by a qualified Gemmologist without using sophisticated equipment | Avoid scratching as may remove the coating | |
| Common | To produce colour in colourless topaz | Very good | Detectable only with an internationally accredited laboratory | No specific care required, see above for more detailed information on jewellery care | ||
| Tourmaline | No Enhancement (N) e.g, chrome tourmaline | No specific care required, see above for more detailed information on jewellery care | ||||
| Heated (H) e.g, green tourmaline | Common | To enhance colour | Very good | Not Detectable | No specific care required, see above for more detailed information on jewellery care | |
| Irradiated (IR) e.g, red, pink, purple tourmaline | Occasionally | To enhance colour | Not Detectable | No specific care required, see above for more detailed information on jewellery care | ||
| Turquoise | Impregnated (I) | Common | To enhance lustre | Good | Detectable by a qualified GEmmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care |
| Reconstructed (R) | Occasional | To produce stones that are available to set into jewellery | Very Good | Detectable by a qualified GEmmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Dyeing(D) | Occasional | To produce different colours than the natural blue | Good | Detectable by a qualified GEmmologist without using sophisticated equipment | No specific care required, see above for more detailed information on jewellery care | |
| Zircon | No Enhancement (N) e.g, green and brown zircons | No specific care required, see above for more detailed information on jewellery care | ||||
| Heated (H) e.g, red, blue and colourless zircons | Routine | To produce and enhance colours | Very Good | Not detectable but assumed due to prevalance | No specific care required, see above for more detailed information on jewellery care |