It has been claimed that the spheres are perfect, or very near perfect in roundness, although some spheres are known to vary over 5 centimetres (2.0 in) in diameter.
Kebulatan batu-batu tersebut dinyatakan sempurna, atau sangat mendekati sempurna, meskipun beberapa batu diketahui bervariasi antara 5 sentimeter (2,0 in) pada diameternya.