I didnt want to hold on to my rings at all--even if they changed the setting etc...but that is just me---and like you I needed the money...
If it has diamonds and sapphires in it I would pay to have it appraised....if you can't go into a jewelry store and tell the sales person you are thinking of having this ring set differently--what would they suggest and then casually slip in how much do they think its worth...most will tell you..