Do they even lase? Definitive ranking of Steven Universe gems by a laser scientist

In the Steven Universe cartoon series, most of the characters are some kind of space alien gem or semi-precious rock. They don't just use the best-known gems, but dig deep into the collection drawers to pull out azurite, chalcedony, various kinds of agates, and even some questionable "gems" like flint.This raises the question (or at least it does for me): which of the gems would make good lasers?I've grouped the gems into four categories according to their pew-pew prospects, starting with:D-tierSorry, no. Here's the thing about laser materials: light has to be able to travel through them. If it transmits light about as well as a brick, there's no way for light to survive and get stronger inside the gem. Even if the rock is a bit translucent, that's not good enough. Light will scatter away before it has a chance to form a strong laser beam.These are your D-tier gems. They might be pretty rocks, but that's about it.C-tierAt least these gems are clear and crystalline, so they won't stop…