When buying jewellery, it’s important to ask if the gemstones are natural or artificial. If they are natural, check if they have been treated and need special care requirements.

Ideally, this information should be included on the receipt as they are not always easy to identify, even by experts, and can affect the value.

Advances in manufacturing technology have also resulted in increasing numbers of synthetic stones reaching the marketplace. Again, these are not always easy to pick.

An NCJV registered valuer™ can help prevent you from falling into the trap of believing a gemstone is of greater quality and worth more than it actually is.

Treatments can be short-lived

Beyond traditional cutting and polishing, gemstones can be treated in many ways to enhance their colour, clarity and durability.

The problem is that some of these processes can also impact the stone in other ways and be short-lived.

Not all treatments are permanent and the stones may deteriorate with normal use and require special care.

Types of treatments

• Bleaching and dyeing – altering the colour of porous or fractured gems by treating them with chemicals. Sometimes gems are fractured on purpose through heating so they absorb the dye more easily.
• Cavity filling – hiding imperfections and improving a gem’s clarity by filling surface fractures or cavities with glass, resin, wax or oil. Filling materials can also add extra weight.
• Heat treatment – enhancing both colour and clarity through high temperatures.
• High pressure, high temperature (HPHT) treatment – changing a diamond’s colour through high temperatures under high pressure.
• Impregnation – giving a porous gemstone greater durability and enhancing its appearance with a polymer, wax or plastic.
• Irradiation – changing a gem’s colour by exposing it to an artificial source of radiation.
• Laser drilling – using laser light to reach dark inclusions in a diamond which can then be treated with chemicals.
• Surface coating –applying a colouring agent to the back surfaces of gems, called “backing”, or coating the entire stone’s surface to alter the colour.

To find your local NCJV registered valuer™