Emerald sits at 7.5 to 8 on the Mohs scale, which sounds robust until you learn that almost every emerald on the market carries internal fractures.
We buy from a single dealer in Jaipur and reject roughly two stones in five. The ones that pass get bezel settings rather than prongs, because a bezel spreads pressure around the girdle instead of concentrating it at four points.
Wearing it
Take emerald off before the gym. Do not steam-clean it, ever. Warm water and a soft brush, nothing else.