Answer: Before you re-oil emeralds, make sure you have actually removed all the old oil. You can do this by slowly simmering — not boiling — the stone in soapy water. Soaking it in a solvent like alcohol will also do the trick.
To re-oil emeralds, all you need to do is submerge the stone in an appropriate solution (oil, epoxy, etc). Next, place the stone and the solution somewhere warm. The back of a stove or a sunny window in summer are great locations. Keep it at about 100° F for a day or two. That is all there is to it!
Donald Clark, CSM IMG
Editor’s note: You could also try this vacuum method for re-oiling emeralds.