Fissures, or cracks, are common in emeralds. Try to avoid those that penetrate too deeply into the stone, thus making it more susceptible to splitting.

Like most gemstones in the market today, emeralds are usually treated in some way to remove surface flaws and enhance color. The most common (and acceptable) technique is to oil the stone with a green-tinted oil to fill in surface cracks. The oil hardens and strengthens the stone, and

improves its green color as well.

In caring for your emerald, avoid ultrasonic cleaners that can remove the oil, or harsh cleansers that can damage relatively soft surface. Clean with a soft, damp cloth and warm water, and a soft bristle brush if needed. The gem has been known to crack when exposed to extreme temperatures, so keep this in mind when wearing your emerald. Regularly check that setting prongs aren't loose or cracked, and have a jeweler re-oil every few years.