There are at least two types of Golden Mirrors with special uses.
One, believed to be a unique item and made out of a fragment of the Curio, is the mirror used by Cecil and Beleth to decipher Reversed Ancient. The object was lost during the invasion of Marali in 426.
In 438, Marali produced two different mirrors to serve as a way to communicate between two people physically apart. One mirror would reflect the the image captured by the other, allowing its holder to see the surroundings of the other person. Those mirrors, perhaps made in bigger quantities, do not work as a reading aid.