Initial points to start with, hold it thoroughly clean. A gentle, moist fabric gently wiped more than your Pukhraj can take away any dirt or grime Which may have settled on its surface. Stay away from harsh chemicals or abrasive products; they can be as well hard on your stone. https://www.apsense.com/article/810029-some-historical-facts-about-sri-lankan-yellow-sapp.html