Caring for your emerald.
Clean it the gentle way: warm water, a drop of mild soap and a soft brush, then dry it. Avoid ultrasonic and steam cleaners entirely, the vibration and heat can open existing fractures or strip out the filler that keeps a stone looking its best. Keep it away from solvents, household chemicals, perfume and prolonged heat for the same reason.
Store it apart from harder stones so nothing scratches it and take rings off before anything high-impact, sport, gardening, heavy work at the sink. Over many years a treated emerald can be professionally re-oiled to refresh its appearance; it is a routine, reversible service, not a repair. Handled this way, emeralds last for centuries, which is exactly why so many of the famous ones still exist.