The jewellery industry is ever changing and throughout its history, jewellers, gemstone and diamond dealers and cutters have always tried to alter or improve the colour or clarity of the diamonds or gemstones.  Initially, the treatements were very simple to administer and equally simple to identify.  For example, applying a small amount of paint to the underside of a stone in order to impart a colour in the stone when viewed face up.  This treatment was very easy to identify because the dried paint on the stone left an obvious indication of tampering.  Through the years, the techniques used for these new treatment   in most cases, the aim of the treater was not to deceive the buyer ratherand techniques needed to identify some of these new and old treatments or enhancements require more advance equipment and a thorough knowledge in gemology.    

Diamonds

            HPHT:
            The colour of diamonds can be altered or improved through the process called HPHT (High Temperature, High Pressure).  The process is quite simply.  Since diamonds were created millions of year ago within very active volcanoes.  The environment in these volcanoes was one of very high temperature, in the range of 2,000 degrees Celsius, and very high pressures, in the range of 60,000 atmospheres. Therefore, the HPHT process aims to recreate this environment in a laboratory and alter the atomic arrangement of the Carbon crystal lattice.  It was found that depending on the formation of the Carbon crystal lattice, the colour of diamond could be altered from a brown or light yellow to more desirable intense yellows, pinks or oranges.  In some unique cases, the diamond’s colour could be changed to whites in the range of H or better.
            There are many key identifing features which identify diamonds which have possibliy been treated when viewed through microscope. Conclusive testing can only be done in laboratroies equipt with more specialized equipment which can analyses the absorption spectra of the diamond.

            Irradiation Treatments:
            Through the use of irradiation, it is possible to change the colour of a diamond.  The resulting colour range is any where from greenish yellow to yellow, purplish red to red and yellowish blue to greenish blue.  The form of treatment is very stable and safe to wear.