The central core is constituted by the convex part (bum-pa) of a stupa which was to be welded to an underlying drum and to a base that it is not possible to establish whether it was originally made of wood, stone or metal. On the drum were placed, in the four directions of space, the four figures of the Jina in embossed and gilded copper. The bum-pa is dominated by a typically Nepali-shaped harmika, above which rises a cusp formed by nine rings and ending in an amalaka on which the support of a rock crystal sphere rests. The further development in height, supported by an overlapping metal structure, is probably a later addition. It presents a succession of three chattras (parasols as a sign of royalty), again an amalaka and a new cusp culminating in the jewel symbolizing the radiance of the Doctrine.