Juice Glass Mystery

One of our wedding gifts was this handy set of 6 small juice glasses in a metal carrying case from Crate & Barrel. In time, 2 of the juice glasses broke, though. For Christmas a few years ago, Tasha gave us a set of 4 juice glasses, same size, with cartoon cats on them. I put them in the carrying case mixed with the clear glass ones. Then eventually enough broke so there were exactly 6, some of Tasha's and some of the original. Anyway, today I was putting away juice glasses and noticed that one of them is a heavy leaded glass, not like the others. There are still 6 total, but 2 are Tasha's, 3 are the original, and there is 1 that has a bigger base and is heavier than the others. Where did it come from? A mystery! I can only assume someone broke one and decided to replace it. But they replaced it with a nicer glass than they broke. And anyway, where do you buy only 1 juice glass?