Getting an appraisal is an excellent idea *if* you think the pieces are worth enough to justify the expense. If the pieces are worth hundreds (not thousands), it may not be worth it.
One step on our odyssey toward a more sane personal economy was selling any of my jewelry that we could get a 'decent' amount for. We discovered that brand names do matter and that there is a hard-to-predict (for non jewelry pro's) relationship between retail price and consignment value. For example, pearls are much less expensive than they used to be but Tiffany's or Mikimoto will still bring some $$, more than non-branded genuine pearls.
We paid for an estimate (make sure the estimator knows you are looking not for 'insurance value'-what it would cost for you to replace the item new & at retail - but for as-is wholesale value, what a store would pay you). We ended up keeping a few things whose sale value was very low in our view compared to the "utility" we got (why sell my former-face-punch-worthy-life fancy french watch for $70?).
We found different places offered us vastly different amounts for the same pieces of jewelry. After visiting 3 places with the appraisal in hand, we mostly sold through a jewelry consignment place in NYC called 'Circa' - they offered better $ than the jewelry stores we visited on that particular day. This was I think 2009. One of the stores tried to convince us that our name-brand stuff wasn't genuine (hello! we had documents and original receipts from the stores and the appraiser had already confirmed their maker marks or whatever they are called) in order to lowball their offer. For specific items (again, I admit our former life was face-punch worthy!) there may be specialists you can find online -- we sold the spouse's 15yo Rolex to a place in Texas (we mailed it in so they could confirm authenticity and then gave us a price).
I learned 1) I will never buy any jewelry (I still have more than "necessary", but less than 90%+ of US folks) and 2)if anyone is going to go ahead and buy jewelry, they should buy used jewelry - just as much bling for less $ and less 'depreciation'.