tell them apart without a UV light when you only have one of them. Like most snapper collectors I had one of the Harrah's New Orleans snappers when news of the light and dark color varieties was a announced. There is a difference in UV marks, but there are a number of problems with using UV marks to find the chip you need on a convention floor. The color differences are not so great that you can be certain about the chip you are looking at is different from the chip in your collection at home. The scan of these two chips does not show it, but there is a difference in the H&Cs that you can see with just your eyes. The chip with the dark colors has H&Cs that have polished appearance while with the light colored chip the H&Cs are dull.