Reply To: 2018 Single Stone Competition Questions/Comments › Forums › General Discussion › 2018 Single Stone Competition Questions/Comments › Reply To: 2018 Single Stone Competition Questions/Comments April 2, 2018 at 4:56 pm #4294 Alan BalmerKeymaster @alanbalmer Jeff, we’re currently talking to our webmaster about updating the competition page. Michael, that’s an interesting question! I don’t see anything in the rules that precludes an opaque stone.