You and others discussed this in a thread in 2023.
https://forum.turquoisepeople.com/t/hopi-silvercrafts-guild/10867/7
Surely Mark Sublette meant that for a Hopi Silvercraft Cooperative Guild artist, collectors look for a sunface hallmark of this type–not for Hopi jewelry generally (such as pieces from Guild artists who also worked elsewhere, or for Hopicrafts).