Size is as-packaged, or the diameter of loose marbles. ("D" is the diameter of round items other than marbles.)
: 5/8 x 1"D
Acrylic marble display cone can be used either up or down, to elevate and display both larger or smaller marbles. The opening at the small end is 3/4" and at other large end it is 1&1/4". Each end is tapered so that it securely "hugs" the sphere it is supporting. Use the small end to display marbles 1-2" in diameter, and the large end to display 2"+ marbles.