"But I rode to the foot of Orthanc, and came to the stair of Saruman; and there he met me and led me up to his high chamber. He wore a ring on his finger." - Gandalf at the Council of Elrond
Saruman's Ring was the ring the Istar Saruman (Also known as Curumno or Curunir) who was sent by Aulë and Alatar.
It is said that Saruman made this ring in envy of Sauron's abilities to create powerful and great Rings of Power.
In the book of the Fellowship of the Ring, it is stated that Saruman had a certain ring around his finger. Saruman said "For I am Saruman the Wise, Saruman Ring-maker..." Saruman was also researching a certain Ring-lore which is also stated in the Fellowship of the Ring book: "Saruman, failing to get possession of the One Ring, would ... have found in Mordor the missing links in his own researches into Ring-lore, and before long he would have made a Great Ring of his own with which to challenge the self-styled Ruler of Middle-Earth".
It is quite certain Saruman's Ring was not a Great Ring but that Saruman had been researching rings, we can safely assume that it wasn't Saruman who created the ring but it was a mere gift from Sauron.
The powers of the ring however, were never revealed, not in the movie nor in the books. However, Saruman did ascribed the ring to have some sort of potency, though it is possible that it have been a bluff on his behalf.
Appearance on the server:
Pavle's Saruman sam ja ring-ilnag