Where they are actually made
Most bowls on the market are manufactured in China, including the frosted bowls sold by brands whose language implies otherwise. When a brand says its bowls are created in the United States, read what that word is doing: the creating being described is often something closer to intention than to manufacture. Resellers downstream then repeat it as made in the USA, which is how a soft claim becomes a hard one.
Some of the higher end bowls do appear to be finished in the United States, and their prices say so. Even then, where a bowl was finished predicts its sound about as well as where a guitar was assembled predicts how it plays. Take the flag on the listing as a grain of sand, and go looking for the measures that mean something.
