One use only. The ring becomes bound to that specific character.
“There are three kinds of men. The ones that learn by readin’. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” -Will Rogers
One time only although its a disappointing that you cant use the same rings for all your character's even if you are married to the same player just so you have more variety between classes.
Well I had also seen the vids that you could reset, well I am here to announce nope.. And you are out of luck. So pick your race and class before committing or be unhappy