[Voralphion]

I think the ring of Saruman didn't have much, if any power. He often seemed to be deluding himself in regards to his own skill and power. He knew much of the lore of the rings and ringmaking and probably though that he could himself make a ring and use it to defeat Sauron and rule middle earth himself. His lore of the rings of power however was lacking and so any ring made by him would not have the power of the either the 9,7,3 or 1. It was probably similar to the lesser rings originally made by the elves of Eregion. At the time of the war of the ring, only Sauron had the knowledge to make rings of power and I doubt he would have given that knowledge to Saruman.