Did you know that the stone on your 2 carat oval diamond ring can be color coated? This can be done in two ways: sputtering and ink staining. The latter used to be the more preferred process, and is performed by dying a diamond using colored ink. These days, however, sputtering, which involves adding a super-thin layer of film to the diamond’s surface, is more commonly used. Other Color Treatment Processes Color treated diamonds cost less than natural colored diamonds, and are nowhere near as rare. This stems from the fact that high quality natural colored stones are becoming harder for consumers to buy, due to rarity and steep prices. As a substitute, one can buy a HPHT diamond, or an irradiated one. HPHT Process In this, a diamond is subjected to extreme pressure and heat. This is only done on higher quality stones. The result is a diamond that looks much better in terms of color, which is then re-polished and buffed. Irradiated Color Treatment Here, minute particle are shot at the stone, and this changes its physical properties. After that, the diamond is heated to high temperatures to induce annealing.