making any 'set in stone' comments about Navajo silverwork is problematic.
coin silver objects from Navajo country are RARE!
I have one...an only one piece made from coin sliver.
true, some early pieces were coin silver...early as in pre-1880...1880's is when the santé fe railroad came through the area, bringing everything one could buy in the east...
including silver plate, wire, and commercially cut stones.
this time period is also when the massive "collection" of native American artifacts occurred...and most of the damage to these ruins, one can still see today.
after the hippy period...when beads an bangles became popular for young people...many of the "Navajo" pieces were in fact created by factories of anglo silversmiths...yet sold as native creations....
many laws have evolved due to people of low morals cashing in on the native market.
it was in early 1900"s, that native silversmiths began marking their work with a symbol, or initials...
the .925, and sterling marks also began to appear, in tune with the rest of the American metal workers.
American Silver Marks on Coin Silver and Sterling - Silver Magpies
Navajo Silversmiths