Yellow diamonds have been produced by treating brownish diamonds. These treatments include HTHP (high temperature, high pressure), irradiation, annealing and coating. Some of these treatments can be reversed or altered if the diamond is subjected to heating during jewelry repair. Coatings are often thin layers of silica applied to the surface of the stone. These can be damaged by abrasion, chemicals or heat.

Yellow diamonds that have obtained their color through treatment should always be disclosed and sold for a lower price than similar diamonds with a natural color. The buyer should also be informed of any special care requirements. Many buyers have no interest in treated diamonds. They want gems with a natural color and are willing to pay a premium for them. At the same time, some people are glad to buy a treated stone because it enables them to get a larger diamond for the same price or the same size diamond at a lower price.