Size is as-packaged, or the diameter of loose marbles. ("D" is the diameter of round items other than marbles.)
These small mineral spheres are suitable for collecting or play. Lapis lazuli is a gemstone that might have come straight out of the Arabian Nights; a deep blue with golden inclusions of pyrite which shimmer like little stars. The use of the word lapis to describe a rich, deep hue of blue stems from this mineral's name. The color is so dark and rich I would think these were dyed if I didn't know better! We were out of these for a while but just discovered a new source and bought them again because they have been very popular - while they last!