I came across a black jar that has R5 on the base. The jar is 9 inches tall and the only daylight you can see when holding it to the light is through two bubbles at the base. How do I know if it is real or reproduction?
It's black? That sure doesn't sound like something that was ever produced as a canning jar, but it could be a real jar coated in something. Can you post a picture?
Looks like one of the "Dream Color" series reproduced in the 70's...although it won't make ya enough to retire, it still commands a pretty good resale value. There were some jars produced in the later part of the 1800's that looked black but were actually a very very dark purple...they were Hartell jars found in an old pharmacy shop......cool jar to have, that you found.