Green and blue would definitely give you a turquoise...and knowing the Rusto colors, it would be a pretty dark turquoise at that.

You might need some white in there as well if you want a true teal, and possibly a dash of yellow to save it from being too 'khaki' !

That's why I'd experiment with little Testors-type cans before I mixed up a bigger batch!
And of course - take notes about the proportions you use...