If you still have the 'piece' - you might try sticking it back. I think one of the Loctite products is made especially for glass, and you can trim the excess, with a craft knife, when dry. I expect the purists wud shun this practise (?), but if nothing else it prevents the existence of a potentially dangerous edge on an unsuspecting eater of cakes. Re big and small - personally, I can't see a proprietry issue of a double tier, ever having the smaller plate at the bottom - maybe only, as you say, when you make up odd ones at home. However, I'm willing to be proven wrong - is there anyone out there who has a commercial set with sizes 'vice versa'.
Re terminology - I get the impression that 'flint' is used for any glass which is technically not coloured i.e. whether it is frosted or smooth. As items they are very collectible, just that they take up a lot of room. Paul S.