I need advice on selling a diamond ring.?

I have a very old solitaire diamond engagement ring. It had belonged to my mother. I need to sell it at this time. If I bring it to a jeweler and he says he will give me $500, for example, should I just take it or see someone else for an appraisal? Also, does age of the ring play any part in determining its worth? Would a diamond ring that sold for $500 fifty years ago be worth any more or less nowadays? Thank you in advance.