Cavernous three-floor market (shopping mall) of goods and pearls. On the first floor, find knock-off bags, scarves, Chinese junk and treasures. On the second and third floors, pearl vendors spread their wares on tables for your perusal. More up-scale shops are on the sides, low-end vendors in the middles stalls.
Vendors sell pearls and stones and can make anything you want in minutes. Bargain hard and don't be afraid to walk away. Every shop has virtually the same thing. If you're worried about buying fakes, understand how to buy pearls before you go.
3721 Hongmei Road (虹梅路3721) just off Yan'an Road.
As there isn't a metro stop that is terribly convenient, the best bet is to grab a taxi. The Hong Mei Road area is a bit of an expat ghetto so you'll have no trouble finding a taxi to take you back downtown (or wherever your next stop is).