All I know is that it’s a factory error on the emerald paint job- early on some pieces were put out that were a darker, more bluish green than the standard emerald. Not many made it to the stores, and not many pop up. They don’t seem to be in all the sculpts, but since it’s an error and not something the factory kept track of, nobody knows for sure exactly which poses it may have been produced on. It seems to be most common on the regular Orientals, but there are male coils and scratchers also, and others I don’t remember… there was a post on it recently, I’ll see if I can find it. It had photos comparing it and emerald.
EDIT: I haven’t found the jade thread, but Rusti has a lovely collection of Orientals, with emerald and jade in both regular and young. You can easily see the difference here.
http://www.windstoneeditions.com/forums/viewtopic.php?t=5080