Another use of opal is in the creation of sewer pipe, ceramic, and refractory mixes. Some synthetic opals are being investigated as flexible semiconductors because of their ability to refract light. Some opals were also used as charms against negative powers. In order to maintain the lustrous appearance of your opal jewelry for a longer period of time, it is necessary to clean it regularly using the appropriate methods. To clean the jewelry, gently scrub it with a soft brush and warm water. After cleaning, remember to thoroughly dry the gemstone with a soft, dry cloth.