The Collaborative International Dictionary of English v.0.48:

Cullet \Cul"let\ (k[u^]l"l[e^]t), n. [From Cull, v. t. ]
   Broken glass for remelting.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cullet \Cul"let\, n. [A dim. from F. cul back.]
   A small central plane in the back of a cut gem. See Collet,
   3
   (b) .
       [1913 Webster]