I really like Gemprint. It’s not something that comes up all that often but it’s sort of like fingerprinting your kids. When you decide you need it, it really comes in handy. Internally I do it on every stone I can because it's a solid way for me to recognize a stone that I've seen before, even amongst a thousand similar stones. The big issue for most people is that the registration results in a discount at many insurance companies. Depending on your valuation, this can cover the entire cost and, as has been pointed out above, it provides a certain amount of peace of mind for not a lot of money.