I personally have not sold gold or silver jewelry. However we do collect numismatics (gold and silver coins) and it is vital that you know the market value for what you have and/or plan to buy.
We have dealt many times with Dallas Gold and Silver and I feel like we did pretty well. They seem to be fair.
Now I do not know any rates for used jewelry and I would never sell unless I had an appraised value but I would certainly deal with Dallas Gold and Silver again.
The last time we went it was years ago and they were in a small location on Josey Lane and LBJ. I know they have recently expanded to some of the burbs so you might have one closer to you.
Good luck.