Manasara 65.72

65.72

tadghanaṃ ca triyaṃśaṃ syādagraṃ tu dviyavāṃśakam
antastalaṃ dvimātraṃ syād viśālaṃ nimnaryavam

Its thickness should be three parts, and at the tip two barleycorn parts; / the inner palm should be two digits in width and one barleycorn in depth.