In small mixing bowl, dissolve gelatin in boiling water. Add orange juice and sherbet. Blend at low speed until sherbet is melted and mixture is smooth. Chill until thickened but not set, about 45 minutes. Fold in oranges and pineapple. Pour into 1-quart oiled mold or 8 inch square pan. Chill until firm, about 1 1/2 hours.