Agate Gemstone Soap Agate Gemstone Soap is good for oily skin, with added oils of nutmeg, avocado and black clay, it cleanses skin and removes grease. Agate Gemstone Soap is a replica of the real stone, reproduced in a high quality soap. You can also buy this fragrant gemstone soap in the sets ‚ Secrets of Arabia 4 and Secrets of Arabia 7.