In my opinion, the price of gold ring or necklace is much cheaper in China. Usually they like to sell some K gold jewelry such as 10k ro 14k here. Some style are mounted with some kind of precious gem or semigem. If your girlfriend like the birth stone, maybe you could choose this kind of ring or earring or necklace. If you will propose, the diamond will be the best. One diamond ring is the best ! :-)

Good luck!