Size is as-packaged, or the diameter of loose marbles. ("D" is the diameter of round items other than marbles.)
Curlicue has at least 5 colors displayed in each marble - colored glass spirals around a solid core - these amazing marbles look better in-hand than can be captured in pictures! I see red/green/blue/pink/and yellow; cyan/yellow/dark blue/pink and purple and others! This is a larger shooter sized marble measuring 7/8 to 1" or 22-25mm.