Unique. When a Gold Ring is tested in a company with the Scroll of Isildur, the result of the roll (or draw) is modified by +2.
"Yet even as I write it is cooled, and it seemeth to shrink, though it loseth neither its beauty nor its shape. Already the writing upon it, which was at first clear as red flame, fadeth and now only barely to be read."
-LotRII