This is a ruby red glass round platter, torte plate, or chop plate. It is 12 1/2" wide. It it not marked or signed, and I have not been able to identify the maker. It looks like Anchor Hocking Royal Ruby in shape with the rim. The platter is in excellent condition with no chips or cracks. I see a few small utensil marks.
Ruby Red Glass Round Platter Torte Plate Plain 12 1/2"