I have only one such a blue bead, though mine is slightly different. Possibly smaller with only 12mm from hole to hole, but with lozenge shaped design on each of the four sides.

What puzzles me - REALLY-REALLY puzzles me - are the very exact shapes of this four decorations. I would not know how to explain this, if the bead were contemporary, but how was such a precision (in glass) possible
~2000 years ago and what was the technique to apply the diamond shapes?