>>I usually work with snakes but decided to get some crested's and the person I purchased them from was saying he looped them and they were a pair. It was crowded so I didn't ask him what he meant by looping them. If you can explain this method of sexing them to me. Thank you

You use a jewelers loupe and you check for pores on the underside of the geckos. It's somewhat difficult to do if you don't know what your doing. How big are the geckos?