Things You'll Need
Small plastic container
Natural emeralds are riddled with fissures and cracks before treatment. Some are also slightly cloudy or opaque in patches due to the natural process of emerald formation. For this reason, raw emeralds are treated with oil, wax or resin to fill these fissures and give the emeralds a smooth, even surface. The most common technique is oiling. Cedar oil is often used because it is colorless and does not dissolve in water. Most emeralds eventually require a new coat of oil, though you can delay the process by keeping your emerald jewelry away from acidic solutions and products containing alcohol. Large emeralds are easy to reoil yourself but small stones should be handled by a jeweler.
Gently clean your emerald of any dirt and grime with warm water and a soft cloth. Rub a dampened cloth over the emerald until it brightens slightly and then dry it off. Remove it, if possible, from its setting or remove any chains from a pendant or earring backs from large emerald earrings.
Pour a small amount of cedar oil into a small, plastic container. Make sure your cedar oil is pure and not cut with other oils like avocado or sweet almond. These oils are often used to cut essential oils used for the skin. Check stores specifically for jewelers who sell the pure cedar oil. Most cedar oil used on emeralds is made from Junipers Virginian cedars.
Place your emerald into the oil and turn it gently to coat all of its faces. If necessary, pour a bit more oil into the container to just cover the emerald. Let it soak for about 8 hours.
Gently remove the emerald from the oil and set it on a soft, folded cloth. Do not wipe the oil off. Wait 24 hours to allow the oil to seep into all of the fissures and seal them.
Wipe away any excess oil.