Walnut gets lighter, and I think wenge might as well.
I agree that UV/direct sunlight is the main factor in wood changing colors. Lots of new high tech finishes come with a UV blocker, but this wouldn't apply to antiques.
The walnut I was referring to is eastern black walnut. I have found some purples and greens in some of my walnut, but usually it starts as a chocolate color then goes to a honey brown. I wish it would darken, but based on my last 6 or so projects, it hasn't.
I have a few hundred bd. ft. air drying outside my shop now.