at 2 inches you've got no chance...
even once they get some size to them its hard...
i think i read somewhere once that if you look at the spangles on their faces the males tend to have defined spots, whereas the female's kinda congregate into a pattern.. but dont hold me to that, that may be for jack dempseys...
Ive had 2 jewels in my affrican tank for a while now and still have no idea what sex they are... though im assuming male