In “Tolkowsky Revisited,” (JCK, June 2002, pages 136 and 138) a sidebar titled “Heads Up” mistakenly attributed Michael Cowing’s diagrams of light passage in diamonds to computer software from Bruce Harding. According to Cowing, “These diagrams and most of the diamond images in my study were computer generated with DiamCalc from Octonus Software.” Cowing also notes that the two diagrams in Figure 1a and 1b “illustrate comparable paths of light in the Ideal cut vs. the poorly cut nailhead diamond to illustrate why the nailhead is darker and much less brilliant than the Ideal.”