As a visible symbol the vajra takes the shape of a sceptre (the emblem of supreme, sovereign power), and therefore it is correct to call it ‘diamond sceptre’.
Govinda identifies the sceptre as the visible, sovereign form of the vajra, whose cosmogonic structure — sphere, poles, lotus-blossoms, axes — encodes the entire unfolding of conscious existence from an undifferentiated centre.
, Foundations of Tibetan Mysticism, 1960thesis