A classic pressed glass tumbler has this mark: A2U and 7. The marks are raised at the bottom, A2U on one side, and a small 7 across from it. I have four of these tumblers. The 7 mark is only on one of them. The others show different numbers. I have been unable to locate either maker or marks. Notable (IMHO) about these tumblers: They are made in 4 parts (4 seams). Any suggestion on where to look up the marks is appreciated. Researched replacements.com site for the most common US makers, Anchor Hocking, Imperial etc. but this pattern was not shown. I realize this is not much info. to go on but a tip on where to look up a mark like A2U would be helpful; perhaps I could take it from there. Posting a photo from my sm.phone taken outside just now. Size: 6" high, 3" across the top. A heavy crystal 'ping' sound. It is definitely not hand-cut, however. Would like to know maker and significance of marks. Thanks in advance for any suggestions!