I would say wear something that is business casual that does not contain any org's colors as the primary focus. For example, I would not wear black slacks and a red shirt. I would agree to leave the pearls at home since that could be construed as interest in a specific org. Navy, I think, would be neutral enough. You obviously won't show up in something pink and green or blue and white, though.
But I've seen interest meetings where women have shown up in that org's colors or worse, in another org's colors.
But whatever you wear, make sure its ironed and not stained, and be sure to mingle with everyone.
Let us know how it went!!! Good luck!