Help me identify this Hopi Artist

I have a beautiful Hopi necklace that I bought in the mid 80’s (see pictures). I was told that the artist was Ella Riggs and there is a stamp of an arrowhead on the back of the Man in the Maze.

Can anyone validate the artist? I am considering selling the piece but there is very little information about Ben and Ella Riggs on the internet.

Also-- the piece cleans up nicely like silver but it is not stamped as such-- how can I tell if it is really silver? Thank you!

<img src=/uploads/db1846/original/1X/adb481cd8853ac177c2ea4dc3406432e23cba293.jpg">

<img src=/uploads/db1846/original/1X/e5653b03875cf7210ac14389e1698013fd676154.jpg">

<img src=/uploads/db1846/original/1X/eeb62530c6803f413ad5428a065f922be65e7cee.jpg">

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