Generally, it is enough that the diameter of the waist bead is 2mm larger than that of the main bead, that is, the diameter of the waist bead is 1 1mm, which can be added or subtracted on the basis of this size. It should be noted that the diameter of the waist bead should not be smaller than that of the main bead. If you think the diameter of the waist bead is small, you can add some more on the basis of 2mm, but not too much.
Half the diameter of the top bead is larger than that of the waist bead 1~2mm, that is, the waist bead is 1 1mm, and the top bead is 12 and 13mm. The size of the top bead must be larger than the waist bead, otherwise the main body is not prominent enough.
When the top bead and the waist bead are well matched, the Buddha's head is much better matched, generally 2 or 3mm larger than the diameter of the top bead is enough.
With a 108 Buddha bead, the diameter of the waist bead 1 1mm, the diameter of the crown bead 13mm and the diameter of the Buddha's head 15 mm, which is relatively conventional. Some players think that with this collocation, the Buddha's head will be smaller, and this can be added or subtracted according to their own preferences. The principle of matching is: the main bead is smaller than the waist bead, the waist bead is smaller than the top bead, and the top bead is smaller than the Buddha's head (when the accessories are much larger than the main bead, you can add some matching beads of different materials to reduce visual conflicts).