Most gemstones can be immersed in a solution of mild detergent and warm water. After soaking for a few minutes, gently clean the stone with a soft brush. Extra care should be taken to remove dirt from the bottom of the setting, a common place for build-up to occur. To remove any detergent, rinse the stone in the same temperature water as the soaking solution.

For diamonds, sapphires, and rubies, bring an equal mixture of household cleaner and water to a boil. Remove from heat and allow the gemstones to soak in the solution until it cools. For stubborn dirt, a soft brush can also be used on these types of stones.

Jewellers use mechanical cleaning procedures to clean gemstones. Some of these methods can be harmful if done incorrectly, so ensure that the cleaning is being performed by a qualified professional. One common method is ultrasonic cleaning, which uses frequency waves to clean gemstones. Since it is considered somewhat forceful, fragile stones, such as opals and pearls, should not be cleaned this way. Steam cleaning is quite effective but can result in thermal shock because of the often-quick temperature change.

Thermal shock happens when a stone is instantly transported from one extreme temperature to another. It can result in cracking because parts of the stone are forced to expand at different times.

Opals contain almost one-third water and are therefore particularly vulnerable to even moderate temperature changes. In hot environments, the heat can cause the water to evaporate and discolor an opal. They can be cleaned in the same mild detergent and water solution as other gemstones, and delicately scrubbed with a very soft brush.

Likewise with pearls - although soaking can result in discoloration, so this should always be avoided. Pearls should be dried after cleaning, using a soft towel, and air-blown dry. This type of stone can be strung on silk or nylon thread, the silk being a better choice because it fails to accumulate as much dirt as nylon.

Common sense is the best preventative measure when caring for any antique gemstone. Hairdryers should never be used to dry freshly-cleaned gemstones, and no pieces should never come in contact with chlorine.