This 1939 Whip-o-Lite Aladdin shade is No. 502-tan. It was also available as No. 501-white. The bottom diameter on the shade is 17 inches from tip to tip of the flutes since it was designed for the Aladdin floor lamps.
The dark lines you see at the bottom of the shade when it is lit are not part of the design itself, but rather a shadow cast by the shade ring and tripod.