This is a very big Aladdin shade! It measures 20 1/2 inches at the bottom, 11 inches at the top, and is 10 3/4 inches tall. It was designed to fit Aladdin's first 12 inch vase lamps and their first floor lamps, which were the 1250 and 1251 "bird cage" floor lamps.
This particular shade is a parchment shade No. 640. I can't date it to the exact year but it had to be made in either 1930 or 1931 since those are the only years the 20 1/2 inch diameter shades were made.
One thing you might note on these big shades is that the top and bottom bands on it are actually sewn to the paper shade material. They are also all hand-decorated.