Diffusion treatment in diamonds involves which mechanism?

• A. It involves melting the diamond to impart color
• B. It involves surface coating to alter hue
• C. It diffuses colored elements into the lattice at high temperature to cause color changes
• D. It is a natural property of all diamonds

Answer: (C)

Diffusion treatment changes color by moving tiny amounts of color-causing elements into the diamond’s crystal lattice during high-temperature processing. At elevated heat, impurity atoms such as boron or beryllium migrate from the surface into the diamond, creating color centers or altering the electronic structure so the color appears throughout the stone. This is different from melting the diamond, which would damage the lattice; from surface coating, which only alters hue at the exterior; and from natural properties, since this color comes from an artificial diffusion of impurities. The result is a color that penetrates the stone rather than being a surface effect.