When Daiyu admires a black jade ring at a booth at Fair Saint Louis, the elderly Asian vendor tells her it is meant for her because her name means "black jade." Persuaded to buy it, Daiyu passes under the Gateway Arch wearing it and finds herself transported to another world, where the continent was colonized from the opposite direction; instead of being an adopted Chinese teenager in the United States, she is, to all appearances, a young woman of the ruling Han class in Jia. Kalen, the kindly white boy who takes her in hand during her initial panic, is a desperately poor laborer a step away from being homeless, but he knows the people who needed Daiyu or someone like her to come to their world, and he takes her to someone who can explain: she must infiltrate the highest level of Han society to send another traveler back to his world of origin.
I like Sharon Shinn's novels, and I recommend them often, particularly to people who don't necessarily read a lot of fantasy but do like romance. The romantic element in this one kind of takes a back seat to the politics, but is still an important part of the story. I liked the concept of many different worlds, or "iterations," made by various gods in imitation of an original world they all thought they could improve on; Jia is not the original, and neither is Earth. Daiyu seems oddly passive for a large part of the story, but she has a brain and she's not afraid to use it.