A fine opalescent grill plate. This is from their kitchenware called Ovenglass (the artware line made in this same formula was called "Foval"), which was manufactured between 1921 and 1933.
It's 10.5" in diameter.
Condition: a few scattered, light marks from use, which can only be seen under close examination.
Reference: Fry Glass Society, "Collectors Encyclopedia of Fry Glass".
Item ID: 3587