Jade was highly valued by the Chinese (more than silver or gold) as a medium for jewelry within China. Concentrated around the village of Fengtain (Eastern Taiwan) there were jade mines that was hand-worked from 1952 until the introduction of roads and mechanical power in the 1970s (technically feasible). Of course such an operation would require slaves/serfs for the mines, a large active European presence in Taiwan, and it would give Europeans something to trade with the Chinese that they didn't quite value themselves like silver. Which kingdom was most likely to made this happen and what would the Chinese do about it?
\\\Edit* Crap wrong forum
\\\Edit* Crap wrong forum