The white featherweights have a very faint greenish tinge. Some people claim that theirs is more turquoise. If the machine is really green (not just slightly so) then it's either a FW that was painted or another machine. The Singer 185's made in the US and Canada were 3/4 size machines, and they were truly green. Here's a picture to compare your machine with -
http://www.using-sewing-machines.com/Singer185.html