How about to differentiate between celebration and the jubilee using either the sign for 'Gold' or maybe '60' and celebration or party?
Have fun what ever you decide!
Duh it's not the golden jubilee (sorry not enough caffeine today) so maybe 60 and the celebration? Or I guess diamond and celebration? But I can't see that diamond has been used in a manual whereas 'Sixty' is in Basic Vocab 4 Page 82.
We chose to use "60" rather than "diamond" because that's what it's about. We felt that if you were explaining why we were celebrating that you would explain that she has been queen for 60 years (although even that is a difficult concept for many)