On his website, Trond Norén Isaksen mentions that "Queen Sonja has had the Maltese cross tiara altered (...). The bandeau has also been shortened and a pair of earrings made out of some of the elements".
Indeed, if you look closely at the earrings worn by Queen Sonja on these pictures (some of them already posted earlier in this thread by Beth), you can see that the four-diamond motif and the diamond cluster are very similar to the motifs of the diamond bandeau: