Castlevania: Symphony of the Night

The Ring of Varda is most likely the rare drop and the turquoise is the other drop.

You must have beaten the game in order to get a Ring of Varda. If you are not playing on a CLEAR or REPLAY save, when you kill a Paranthropus and it would have dropped a Ring of Varda, it will instead drop a Turquoise. Once you beat the game, Paranthropus' will be able to drop Rings of Varda. Getting a Turquoise from a Paranthropus will not prevent them from dropping a Ring of Varda in the future, once you meet the requirements.

It's like Spherix said - you have to have beaten the game first. Also, it helps a lot if you have 2 of the "ring of arcana" equipped.