Diamond Treatments
The sparkling diamond in your ring, earring, pendant or bracelet did not come out of the ground perfectly polished and faceted. Human intervention is necessary in order to create the brilliant masterpieces you see set in jewelry today. Recutting and irradiation are only two of many treatments diamonds undergo in order to enhance their appearance.
Recutting
Diamonds are one of the hardest natural substances on Earth, but they can be chipped or even broken when pressure is exerted on them. For example, diamond setters may accidentally chip the side of a stone and will have to recut them. Also, diamonds with corners like princess cuts are especially susceptible to chipping since their corners are relatively weaker and thinner. What jewelers do, then, is smooth out the side to make the chip less noticeable. Since a diamond can only be scratched by another diamond, jewelers use a large wheel sprinkled with diamond dust to smooth out the chip. As the wheel spins, the diamond grinds against it to achieve the desired shape. Diamond recutting is also employed to improve the diamond's clarity. Sometimes, an inclusion is very close to the surface of the diamond and in order to upgrade the stone to a better clarity, jewelers will pare down the diamond to get rid of the inclusion. Therefore, carat weight is exchanged for improved clarity.
Irradiation
Irradiating diamonds to change their color has been around for a long time, but the first attempts at this resulted in radioactive diamonds. Procedures have since changed and irradiated diamonds are safe to wear and can withstand the wear and tear of everyday use. Several methods are used to enhance or change a diamond's color, including subjecting diamonds to nuclear reactors, linear accelerators and gamma ray facilities. Irradiation treatment changes only the surface color of the diamond, so the color is more intense in spots where the diamond is thin (like the culet). Diamonds, when first exposed to radium salts, resulted in a green color. Now even pinks and blues are produced through irradiation. Natural fancy colored diamonds were also exposed to radiation beneath the Earth's surface, so it would be difficult to tell natural fancies from color enhanced stones. Highly sensitive equipment is used to differentiate between these, but they are usually available only at gemological laboratories. Therefore, it would be wise to have the stone examined and appraised by an independent lab before purchasing it.