The Three Elven Rings

[blantyr]

Originally Posted by Inziladun

Even though Sam did not recognise Nenya for what it was, I don't think that suggests the ring itself had properties of invisibility. It was dark at the Mirror; Frodo saw the starlight glint on the ring's stone, and, having borne and worn the One, he knew what Nenya was.

I suspect Galadriel's pretense of being the evil dominating wielder of the One Ring had something to do with Frodo spotting Nenya. I believe she actively used Nenya before it was spotted, and used it as a light source. It's hard to be an invisible light source.