Stoneware Periwinkle Disks Posted January 23, 2008 Natalie This periwinkle glaze practically dances over these stoneware disks. I impressed these with a handmade mold, bisque fired them, then glazed and re-fired them. There are 7 in this set. Approx. 8 mm hole to hole, 16-18 mm wide. Find there here.