To wear a ring on the middle finger of the right hand is sunnah, the Prophet, peace and blessings be upon him, used to wear it.
The meaning of the ring is that you cannot take a piece of silver, to mould it as it is and to put it on your finger. Before being worn it has to pass thorough the fire and be forged, hammered. Only then it may contain its secret: the precious stone.
The Sufi way is like this: to reach the treasure you have to pass through the fire.
The Prophet King Solomon had a famous ring, now it belongs to Maulana. When he wears it, it is hypnotic and you cannot resist you have to look at it. It is like having a lamp on his hand. One day everyone noticed it and they asked him and he had to say what it really is. You feel that all the secrets and powers are reflected in that big red ruby, it is amazing. How it came to him we do not know.