In the back alleys of the financial district, you'll find this strange-looking shop. It's actually a wholesale jewelry market. Jewels such as diamonds, emeralds, white jade, coral, and also gold and silver are sold here. The price of the jewelry and other precious stones is 30-50% lower than elsewhere.
The shop advertises that an official from the Ministry of Public Security is always on hand so that you don't need to worry about the quality of products. I can't affirm or deny this, but it's certainly worth a look. After purchasing them, you might later take loose stones to a jeweler and have them set in your own custom jewelry.