When cleaning jewellery with soft stones such as opals, onyx, or pearls use Connoisseurs Delicate Jewellery Cleaner or Connoisseurs Dazzle Drops Advanced and follow package directions. If the pendant doesn’t have prongs holding in the stone, it could be set with glue. In that case it’s more delicate. Wet the brush with the cleaner, don’t submerge the jewellery in the cleaner, and gently brush the jewellery and rinse off with water.