My girlfriend has a diamond ring that she inherited and wants to sell.

We sent it to be valued by IGR (International Gemological Reports), the valuation is for insurance not resale purposes but I'm assuming that it can act as a useful guide price. The valuation has pleasantly surprised us both.

It's a cluster ring set with three round brilliant cut diamonds weighing 0.55ct approximately, colour G-I, clarity SI. On both sides of the diamonds there are fourteen round brilliant cut diamonds weighing 0.56ct approximately, colour GI, clarity SI.

Never having done this before, what are the best avenues to explore? Is eBay worth a try or are there better/safer ways?

Thanks in advance.