You could use the Marlett or Wingdings* font to get symbols, or else set the expression display representation to Image. You can use the builtin images (click the Images tab at the bottom of the expression editor), or you can load your own. Search for Bundle Info Load for more information on loading your own images.
*Wingdings 2 has star symbols
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein