Gray...Here is how I knapp mine...Take a finishing nail about 3 inches long and cut or file the point off...I have a small brass hammer with a screw driver built on it for adjusting the frizzen...I put the hammer at half ****, hold the nail at a 90 degree angle to the edge of the frizzen and hit straight down with that little brass hammer...I move along the flint until it's sharp...I only knapp off a 1/32 or so of the flint and probably move the nail 5-6 times along the flint...

Also...After several shots when you get less sparks, flip the flint over and shoot, it will knapp itself...