Jelly beans are subjective in size, I've eaten more than my share.some are like small grapes and some like Tic Tacs.
Smithsonite is a zinc carbonate. Green color comes from copper, there are other colors. It is a rare stone, it is a softer stone. It is not often found in jewlry because it is soft. Rounded stones abre very rare. It is more a collector's stone than jewelry but that will make it unique in the ring you have. Can't tell you how much it is worth because I find things are worth whatever someone will pay.