Ring Off/On Bolt & Nut by Uday - Trick

The magician shows a large brass bolt and nut. He asks for the loan of a ring, or offers one of his own for inspection. Showing his hands empty, he puts the ring underneath a hanky and moves the hanky over bolt and nut. Instantly he removes the hanky and the ring is on the bolt BETWEEN the nut and the closed end of the bolt! The nut is half-way along the bolt and it would take a lot of time to unscrew the nut, put the ring on then screw the nut back on the bolt. Yet the magician has done it in a flash!