What does 925 qt mean on a ring?

Well, darling, "925" on a ring means it's made of sterling silver, not some cheap knockoff that turns your finger green. And "qt" is just shorthand for "quartz," a lovely gemstone that's probably sparkling on that ring of yours. So, in conclusion, you've got yourself a sterling silver ring with a quartz stone - not too shabby, if you ask me.