Hi. First, I want to apologize for the unbridled vagueries I'm about to unleash. As I'm at work and don't have time to find out if this question has been answered, I'll simple motor on and presume upon your forgiving natures. ;)
The Sihedron Ring detailed on pg. 37 of Spires on Xin-Shalast states that it has an aura of moderate abjuration and illusion. The requirements to craft this ring list: Forge Ring, endure elements, resistance and shield.
What I'm curious about is where is this power derived from?
"At will, as a standard action, you can use the Sihedron ring to change the appearance of your clothing or armor into any other kind of clothing or armor..."
I was considering including a ring with only this specific quality as a random treasure but I don't see what in the list of requirements would be responsible for it.