Mine actually fluctuate a lot between shades of blue, green, and gray. :o It doesn't necessarily happen over night, but it's something I've noticed and kept track of, making sure to use the same shirt color and lighting as benchmarks:p From what I remember it has to do with how your effective your body is at making efficient pigment producing proteins.
Links: http://www.thetech.org/genetics/ask.php?id=30
http://www.straightdope.com/classics/a971205.html (I'm hoping for option 2>_>)
I tend to be in the lighter shades. Nothing extreme usually, except sometimes with my natural eye color, blue, which can get a bit sapphire like. Like I said, I try to make sure I have some sort of benchmark for clothing, since clothing color can affect how your eyes might look.
I'm happy with my 'default' blue though:p
01-Oct-2007
01-Oct-2007