This is a vintage milk glass teacup by Federal Glass.
It features a black and gray scribble pattern near the rim of the glass, an opalescent tint to the cup, and the brand's marking on the bottom.
The cup measures approximately 3.75" in diameter, 4.5" wide including the handle, and 2.5" tall. This teacup was made in the USA.
It is in very good pre-owned condition.