Maintaining a clean diamond can sometimes be difficult, as jewelry settings can obstruct cleaning efforts, and oils, grease, and other hydrophobic materials adhere well to a diamond's surface. Some jewellers provide their customers with sudsy ammonia cleaning kits. Some other jewellers sell small ultrasonic cleaners. Home-based cleaning methods include immersing the diamond in ammonia-based or ethyl alcohol-based solutions, or even a solution of mild grease dissolving detergent and warm water.

 

Cleaning can damage some jewelry. For example, some class rings are coated with a dark pigment to reduce their shininess. Ultrasonic cleaning can remove this coating. Also, many gems (such as emerald and pearl) are soft or porous. Cleaning agents can erode or infiltrate these gems. Ultrasonic cleaning is also contraindicated for opals, tanzanite, amber, and any gemstone that reveals a high degree of internal fractures. Examination prior to cleaning is a good practice as ultrasonic cleaning is an aggressive method.