Leaving them in bunches, wash grapes.
While still wet, sprinkle with sugar.
Put in a freezer storage container and freeze at least 2 hours.
Melt the chocolate in double boiler over hot (not simmering) water.
Use a toothpick to dip the orange segments in the chocolate.
Place segments on baking sheet lined with wax paper and store, covered, in the refrigerator to harden.
Just before serving, place frozen grapes in the middle of a platter.
Surround with chocolate-dipped orange segments.