I've always known lozenge as being a diamond shape. People will call oval shapes lozenges incorrectly because of the term 'throat lozenge' Which today, we know as a halls mentolyptus oval type shape. However, the ORIGINAL throat lozenges were actually rhombus or diamond shaped because it was the easiest way to manufacture large quantities of them. I'm not sure, but I think smith brothers throat lozenges still are that shape. I remember when I was a little kid my Grandpa always had a pack of cough drops with him and they were always diamond shaped. The term 'throat lozenge' is still used today for cough drops even though many of them are oval shapes.