Dry it on the stalk until late fall. Wait until the ears are completely brown and dry and the individual kernels are as dry as possible, begin to shrink and pull away from each other. Otherwise it will just mold.

Dave

AND ... be aware that pollen may have blown in from somewhere else - a duifferent variety of corn - so your next crop might not be "Glass Gem".

Pick out the clearest, brightest seed to plant next year.