I use Blue Diamond and have been using it for a few years now. I always take a cube with me to the bowling alley to play on the barboxes. A couple nights ago, a kid on the table next to me just grabs it without even acknowledging me. He just starts grinding the thing vigilantly on his tip for like 5 seconds. Awww, hell naw! I grab for a cored piece of Master's chalk from another table hand it to him and tell him that's my chalk and that I brought it with me. I don't care if he was a kid. I'm ruthless when it comes to my Blue Diamond chalk ya'll!