Letters to the Editor Humans Letters from the April 16, 2005, issue of Science News By Science News April 12, 2005 at 6:33 pm - More than 2 years ago Share this:Share Share via email (Opens in new window) Email Click to share on Facebook (Opens in new window) Facebook Click to share on Reddit (Opens in new window) Reddit Click to share on X (Opens in new window) X Click to print (Opens in new window) Print Ax questions, hard answers Another hypothesis for the polish on the Stone Age corundum ax head is that the Stone Age people never had absolutely pure corundum, which indeed would have required diamond to polish (“In the Buff: Stone Age tools may have derived luster from diamond,” SN: 2/19/05, p.