Published encyclopedia and visitor-education accounts describe the roundels only in prose, as massive circular panels hung from the four dome piers, without giving a measured diameter or any other numeric dimension, and no published architectural survey of the mosque's interior fittings could be found.
What would resolve this A published architectural survey or conservation report of the Sultan Ahmed Mosque's interior fittings giving the roundels' measured diameter, or a direct measurement taken and published by a future visitor or researcher with access to the mosque's own restoration records.
OpenOttoman architectural history, historic building conservationThe Divine Script: Decoding the Calligraphy of the Blue Mosque (bluemosque.tr)