I've been a customer of LandOfMarbles for several years. They have a wonderful assortment of quality marbles. This order was for an 11 year old autistic boy. He was "over the moon" with excitement when he received the package. I'll keep buying.
Size is as-packaged, or the diameter of loose marbles. ("D" is the diameter of round items other than marbles.)
Wurlitzer has a zig-zaggy twisted core of dark yellow, red, and dark blue, on a white core. The core is encased in crystal clear glass topped with black lines mirroring the zig-zag core which creates a great sense of depth.