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!