> I really like the pint-and-a-half mason jars that some speghetti sauce
> comes in. ...................

Yeah. Classico spaghetti sauce comes in square Atlas Mason jars. The ones I
like are clearly marked with levels at 4oz, 8oz and 12oz and there is room
above the 12oz level for another 3 oz flush with the top of the jar, about
15 ozs, perfect size for jams.

When they make these jars, they must brand them when they are at glass
melting temperatures, since all the markings are pressed right into the
glass.