The same holds true for several other fragrances as well. If you hold a flashlight right up against the back, or for that matter the front of a GIT bottle, you can see the remaining amount of juice left. You can also pick up a purplish hue to the bottle. Same holds true for Antaeus, and numerous other fragrances, that you might think the bottles to be black. That or the light has a way of distorting the color spectrum. Either way I'm not smart enough to figure that stuff out, but I do know It works.