Heat grill. Alternately thread ham, pineapple and tomatoes onto four 10-inch metal skewers. In small microwave-safe bowl, combine jelly and mustard. Microwave on HIGH for 1 to 2 minutes or until jelly melts. Stir to combine. Brush 3 to 4 tablespoons jelly mixture over kabobs.
When ready to grill, place kabobs on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 10 to 12 minutes or until thoroughly heated, turning once. Serve with remaining jelly mixture.