Gemstones must be clean to display their true brilliance, colour intensity, lustre and special optical effects.
Simply wiping the stone with a damp then dry cloth, is normally sufficient to revitalise gemstones to full effect.
But over time, dirt accumulates around recessed stones and intricate jewellery metalwork, especially at the back of settings. Chemical cleaners and ultrasonics are commonly used to effectively remove this dirt, but not all gemstones can tolerate these methods.
See below for the suitability of chemical cleaners and ultrasonics for each gemstone and a normal cleaning method that may be used.
Also take note of the Special Precautions necessary for protect your gemstone from colour degradation and physical damage.
Chemicals may remove dyes, oils and wax fillers from treated stones.
Porous stones may be stained by cleaning fluids.
Chlorine can discolour low carat gold by attacking the alloys within the metal.
The presence of acids in solutions will damage some stones.
Read the product instructions fully before using chemical cleaners.
Beware that some gemstones are Incorrectly Named. Trade names may describe a 'different species of stone'
Ultrasonics use high frequency vibrations to shake loose the dirt lodged between metalwork and the gemstones. Ultrasonics may damage some gemstones types. All heavily included gemstones are vulnerable to ultrasonics. Fracture filled and surface filled stones may lose their fillings.
Check with a jeweller for advice on your stone before proceeding.Positively identify your gemstones before using ultrasonics, as many stones look similar to others, but some types 'will be damaged' if this method of cleaning is used.
Before using a home ultrasonics device, have the stones identified and checked for inclusions or enhancements that may render this method of cleaning a risk. A jeweller or gemmologist will advise on this.
Steam cleaners can remove dyes, oils, wax fillers and other surface treatments. The heat from steam can also effect any stone that is prone to damage through thermal shock including 'heavily included stones'.
Boiling is used as a cleaning method, but few gemstones can tolerate this method, untreated diamonds are one of the exceptions.
Filled fractures may come loose, due to the difference in expansion between the gemstone and the filling material.
Porous stones can be stained if soaked in solutions. Dyed, oiled and wax filled stones may loose their colour and take on a pale or dull appearance..
Caring for gemstones requires knowledge of each individual stone, what damages one stone may leave another unaffected.
Gemstones are made of chemicals and as such may be harmed by other chemicals.
Temperature extremes or sudden temperature changes may affect some, but not others.
The severity of damage caused by accidental physical knocks varies throughout the gemstone range
Separate gemstones and jewellery pieces, by storing in sectioned boxes or wrap gemstones in paper. Otherwise damage may occur when harder stones contact softer stones, or when any stone contacts gold and other precious metalwork.
Do not lift or hold a jewellery piece by the stone or pull at the stone, it may become loose in it's mounting and may eventually fall out.
Be aware of the durability of the stone and the situations in which it can be worn (working environment). Durability is a combination of hardness, toughness and susceptibility to chemical erosion. All factors must be considered.
Remove rings before heavy work; otherwise the gemstone may loosen in the setting or be damaged.
Softer or brittle stones may suffer facet damage. When purchasing these stones, consider an emerald style cut; this cut was designed for better facet protection. The metalwork design may also provide extra protection for these gemstone types, especially when the stone is recessed.
Although diamonds are the hardest of all gems they possess perfect cleavage and may be chipped if struck against a hard surface.
Exposing gemstones from one extreme temperature to another, in a very short time, will cause 'Thermal Shock' in heat sensitive stones.
When wearing rings: Avoid putting your hands in hot water or removing trays from the oven.
Do not put your hands over a hot vent when coming in from the cold (house heater or car vent etc).
In the above situations, sudden heat applied to an opal can quickly remove the water content and crack the stone.
Some gemstones can tolerate extreme temperatures and are unaffected by the heat applied, during jewellery repairs.
It is advisable to positively identify a stone before any repair work is carried out. Mistaken identity may prove expensive.
The colour, or colour intensity, of some gemstones does not remain stable after heat-treatment or irradiation. The treatment may be affected by high temperatures, strong light or both. Some natural stones also fade under these conditions.
To avoid this happening, try not to wear jewellery at the beach, when in strong sunlight or when swimming.
If working under strong artificial light, shade the gemstone or remove the jewellery.
Keep your policies up-to-date and be aware of increases in market value.
Records of your jewellery should include photographs, weights, measurements and purchase information.
It is important to know if a gemstone has been treated to enhance its appearance. If unsure, check out the treatments that are typically applied to the gemstone in question, and take the appropriate precautions for those enhancements. See 'Gemstone Treatments' below.Top of Page
Most gemstones on the market today have been treated in some way. If they weren't there would be few gemstones available on the market. Often the treatment finishes off what nature started, by applying the heat and/or radiation that was terminated pre-maturely during the stones natural creation.
An awareness of treatments is required to protect the enhancement from any possible degradation. Applying the correct care method will ensure this and protect the gemstone from damage. This includes physical damage - chipping or cracking and visual damage - colour changing or fading.
The following is a brief explanation of some of the treatments in use today.
This is the most common form of treatment carried out to enhance a gemstone. Heat treatment may change or intensify the colour and/or reduce the visibility of inclusions to improve the clarity. Heat may be applied or a Flux (chemical additive) may be added during the process to fill (heal) surface reaching cavities.
Some gemstones are heated to create inclusions to authenticate their appearance.
Following heat treatment, the colour remains stable in some gemstone types, but others may fade or revert to their original state. This may happen if they are subject to either strong artificial light or sunlight or high temperatures. Which of these factors affects the stone is dependant of the gemstone type.
Stones subject to this treatment include: Some fancy coloured diamonds, sapphire, beryl, topaz, quartz and tourmaline.
Precautions: Avoid exposure to strong heat and/or light to any treated gemstone that is known to be susceptible.
Irradiation is commonly used to enhance gemstones, some gemstone types are irradiated and then heat-treated,
This process is used to produce blue topaz from brown topaz, the resulting colour remains stable.
Some irradiated stones fade when exposed to strong light, this may happen during prolonged periods of sunlight or artificial light exposuret. An example is tourmaline.
Stones subject to irradiation treatment include: Diamond, sapphire, beryl, topaz, quartz and tourmaline. The stability of the treatment varies for each stone type.
Precautions: Avoid exposure to strong heat and/or light to any treated gemstone that is known to be susceptible.
Oil is used to fill cracks that reach the surface of the gemstone, improving the clarity and colour of the stone. Reflections from cavity walls are no longer seen and colour beyond the cracks becomes visible. The oil may contain a dye to enhance the colour further: it is a common and accepted practice in some countries.
The oil eventually dries out and the stones appearance diminishes. Once this happens dirt may collect in cavities and be difficult to remove safely. A professional is then recommended to clean the stone and re-apply the correct oil.
Stones subject to this treatment include: Emeralds & rubies.
Precautions: For stones that may be oiled, check during purchase to see if the stone has in fact been oiled and, if acceptable, ask for details of the oil used. Re-oil occasionally to prevent the above problems. Periodic professional cleaning is advisable for expense stones.
Treatments are applied to increase the physical integrity and appearance of the gemstone by:
Stabilising porous gemstones through impregnation.
Repairing surface depressions of stones that undercut during cutting and polishing (pitted effect).
Filling cavities in cracked stones or laser drilled stones (glass is also used)
Some gem material is reconstituted and formed into stones by bonding crushed material in resins, turquoise is one example.
Gemstones subject to polymer and resin treatments include: Jade and natural turquoise.
Precautions: All polymer treated stones should avoid contact with solvents and should not be exposed to extreme temperatures.
Australian Andamooka matrix opal undergoes a sugar acid treatment to greatly enhance the opals play of colour. This is achieved by boiling the opal cabochon (already cut and polished) in a sugar and acid solution. This changes the opals normally light or white base colour to black. When seen against a black background, the opals ‘play of colour’ is intense, giving the treated stone a very attractive appearance.
Precautions: Beware of re-polishing these gemstones with abrasive wheels as the colour only applies to the surface of the stone to a depth of about one millimetre.
Pale or near colourless gem material is 'Surface or Lattice Diffused' to apply a thin 'skin-deep' layer of colour. The finished stone appears as a fine example of the gemstone type.
Gemstones that may be diffused include: Sapphire and ruby.
Precautions: The surface colour of the stone will change if the stone is damaged or if re-polishing of facets is applied using abrasive wheels. Extra care is required to protect these stones. Some stones on the market sell at unexpectedly high prices, considering the nature of the enhancement.
Beryllium diffused corundum (ruby and sapphire) is fairly recent to the gem market (around 2001 onwards). The process diffuses beryllium into corundum to create typically yellow, orange and brown colours from pale or nearly colourless material. It can also change the actual colour and transform dull coloured corundum into vibrantly rich coloured material. The diffusion may be close to the surface or may penetrate the entire stone. Beryllium may also be added during another treatment process, for example, treatments that fill surface reaching cavities.
Precautions: Unless known, the depth of colour penetration may be very small, restricting any re-cutting or polishing. The colour may be removed and the stone would revert back to it's original colour.
Lead glass filling is a process applied to corundum (both ruby and sapphire) to fill surface reaching cavities. The number of cavities may be small or extensive, so that very poor material may be treated to produce gemstones that look to be of high quality. Lead glass filled corundum is susceptible to damage from mild acids and physical knocks. This process has enabled many stones, especially larger stones, to appear on the gem market that would not have been possible in the past.
Precautions: Do not clean with abrasives, harsh chemicals or acids (including lemon juice). Avoid using ultra sound cleaners, use a mild soap solution instead. Be careful of damage by physical knocks, rings are better used as dress rings, as everyday use may increase the risk of damage. Altering rings (ring re-sizing) with the stone mounted is not possible as high temperatures will damage the stone. Inform the jeweller that a stone is lead glass filled before undertaking any re-sizing or repair work.