There's a jewellers at the top of the high street that sells very nice, quality jewellery.
Can't recall the name, but it's on the right hand side as you walk down from the Airport road end of the high street. I.e. on the opposite side of the road to Sofra Restaurant
Sorry, not brilliant directions, but hope it helps anyway.
Wherever you buy HAGGLE. If you see something take your time and don't buy it immediately, go back and look over a few days. I recently bought a little ring. Jeweller wanted €700 and after a few days of haggling got it for €300. Valued at home €900. Good luck, hope you get something beautiful!