With these guys I'm not sure off the top of my head, but I could do a little research and find out for you. If your interested in breedeing them it's pretty easy if you buy a group of about six when they're still pretty small (around 1 to 2 inches). They'll pair up naturally and spawn for you all the time. Once two of them pair up you'll probably want to take the rest out of the tank (unless it's a pretty good sized tank) to avoid them beating up on everyone else. I used to have a breeding pair in a 29 gallon, but that was when I was like 11 or 12, and I can't remember the difference in males and females now. But I do remember them having babies all the time. Also, I was pretty young, and made the mistake of leaving the other jewels in the tank after they paired up. The two got so territorial they killed the other four. I also remember doing a water change and having one of them swim up and bite my hand.
But I'll do a little research during the night and let you know what I find out.