A Good Return on Old Gold

I am going to start doing some research on the amount of money that can actually be made on sending in old jewellery into one of the many postal gold companies.  I have seen plenty of them advertised on television, on the Internet and around town and have heard that it is a good option to make some quick cash.  I do have a lot of old, gold jewellery pieces that I never use just sitting wasted in a draw.  I realize I will never be able to get their full value back out of them so if I can get even a decent return from one of these companies I will probably send them in to be melted down.