Thank you very much Rockchick1984 I really appreciate the advice. I have got three valuations from auctioneers (one online via email) and they differ considerably, so I'm confused and unsure whether to proceed this way.
I have been brought down to earth re the insurance valuation, jeweller's selling price, trade value, again, big differences. I had no idea the mark ups were so large in jewellery, guess there are costly overheads to be factored in to the end figure.
I had considered eBay but hadn't thought of the local collection angle, which answers my 'who would commit to buying without seeing' query.
Ask at local independent jewellers and pawnbrokers - its the quickest way but you're unlikely to get anywhere near the price you would get selling it yourself as they (understandably) want to make as much profit selling it on as possible.
Aside from that, eBay is actually pretty good especially if you have an independent valuation/diamond certification for it, you can always advertise it as local collection only so the buyer has to come and collect it from you and sees it prior to payment.
Is anyone able to give me some advice on how to get the best price for secondhand jewellery? I am looking to sell a 3 stone diamond ring (2 carats in total) but haven't a clue where to go. It's not something I'm happy to stick on ebay, really. Many thanks in advance.