When time came for the shepherds to hold their customary assembly in order to prepare their monthly report to the king about the state of the flocks, he came too, wearing this ring. While he was sitting with the others, it chanced that he moved the collet of the ring around toward himself into the inside of his hand; having done this, he disappeared from the sight of those who were sitting beside him, and they discussed of him as of someone who had left. And he wondered and once again feeling for the ring, he turned the collet outwards and, by turning it, reappeared. Reflecting upon this, he put the ring to the test to see if it indeed had such power, and he came to this conclusion that, by turning the collet inwards, he became invisible, outwards, visible.

Having perceived this, he at once managed for himself to become one of the envoys to the king ; upon arrival, having seduced his wife, with her help, he laid a hand on the king, murdered him and took hold of the leadership."

So, what if there were a Second Ring of Gyges.  Mabye it was silver with a gold collet?  A ring that was given to a just person.  If that ring were given to a just person then would the fear of punishment no longer exist and the person would become unjust or is justice something like the desire for health (we all want it)?  What would you do if you knew you could never be discovered?  Is this the origin of Tolkein's ring of invisibility?