How Do I tell its a pewabic tile?

[Mark The kid]

I found some tiles today and they look just like pewabic tiles, there bule and green. There is nothing on the back of them, no stamps just flat. the tiles are sometime from the 1920s to 1930s. I just want to know if these are pewabic tiles.

[Maof]

http://www.pewabic.org/about

maybe their website can give you some info. i have several pieces but they're stamped

[Gistok]

Check it with a Geiger Counter.... LOL... some of Pewabic founder Mary Chase Perry Stratton's irridescent glazes were found to be radioactive...