In a medium microwave-safe bowl combine semisweet chocolate, whipping cream, and butter. Microcook, uncovered, on 100% power (high) for 1 minute. Remove from microwave and stir until smooth. If necessary, return chocolate mixture to microwave and cook on high for 30 seconds more; stir until smooth.
Stir 2/3 cup coconut into the chocolate mixture. Cover bowl and refrigerate for 1 1/2 hours. Line two baking sheets with nonstick foil or lightly greased foil. Drop chocolate mixture from rounded teaspoons onto prepared sheets. Cover with waxed paper; freeze for 10 minutes.
Meanwhile, tint remaining coconut, if desired, by combining coconut and 1 to 2 drops of gel pink food coloring or red food coloring; toss until coconut is tinted. Roll the chocolates between the palms of your hands into round balls, wetting hands if necessary. Roll the chocolate balls in remaining coconut; cover and refrigerate.
Let truffles stand at room temperature for 15 minutes before serving.