5th edition has this
and in 2011 a brother to your cuff was also searching for the same info
https://925-1000.com/forum/viewtopic.php?t=24189
https://www.icollector.com/Navajo-Turquoise-Coral-Inlay-Silver-Watch-Band_i13407202
https://forum.turquoisepeople.com/t/help-with-two-hallmarks-one-n-or-z-and-bear-track/2315/2?u=steve