You may take your jewelry pieces to some reputable jewelry stores, pawn shops etc to find out how much they may be willing to pay for them, you will get different ranges of rates or values from these, you will also need to shop around too, some of these stores/shops will pay better than others.
In order to provide you with a quote or rate, such stores or shops should be able to provide you with some analysis of what makes up your jewelry pieces, like the precious metals and/or valuable natural gemstones they may contain etc for free, since that is what will mostly determine the value of your pieces. Your jewelry pieces will not be valued for resale by the retail prices you may have paid for them but by the worth/value of the precious metals and/or valuable natural gemstones in them.
If you have the jewelry pieces’ certificates and some other information from your original purchase documents/receipts too, you should be able to get this type of information and details from there too. With that you will be able to do some research to find out if the rates that are been quoted for you are fair enough.
You will need to know exactly what each of your jewelry pieces contain in terms of their precious metals and valuable natural gemstones, in order to get the best value for them with anyone, on ebay and pretty much anywhere else too.