Here's the missing piece, and it couldn't be more beautiful. Puzzle solved!
This is a caramelly piece of agate carved by the late, great Dieter Lorenz, the lapidary from Idar Oberstein, Germany. Idar is home to many of the greatest lapidary artists in the world. Lorenz signed this one, and we added the 14k yellow backing and 18" chain. It hangs 1.25". One of a kind!