Consecrating an Atash Bahram, the highest grade of sacred fire, is the most elaborate ritual undertaking in the religion. Sixteen fires must be gathered from prescribed sources: from a corpse-burning pyre, from a dyer, a king or ruling authority, a potter, a brickmaker, an ascetic, a goldsmith, a mint, an ironsmith, an armourer, a baker, a brewer or distiller, a soldier, a shepherd, and — the difficult one — a fire kindled by lightning, which may require a long wait. Each is purified through repeated transfers, the pyre fire requiring the most, and the whole process demands over a thousand hours of priestly ritual and can take a year. The sixteen are then united and enthroned. There are nine Atash Bahrams in existence: eight in India, four of them in Mumbai, and one in Yazd. The Iranshah at Udvada in Gujarat is the most venerated, and the community holds that its fire has burned continuously since it was installed there in 1742 and derives from one brought from Iran with the original refugees.