You might have better luck doing some thorough internet searching. I know nothing about the jewelers around town, but there are lots, and no doubt there are lots of postings on the internet about found treasures, great shops, and places to avoid. Good luck!
Thanks for the reply. I didn't bother to hunt for a reputable one in the end as the workmanship didn't seem as good as HK and it would have taken up too much time. Had a fantastic time in the city anyway.