Here's a few photos of my #2 saddle, showing how the color of the leather has changed over time.

When I first cut it from the hide, it was a light tan. Here it is with the saddle I was restoring:
https://lh6.googleusercontent.com/-J...2/IMG_5484.JPG

To form the leather, I have to soak it. This photo was taken around Sept. 1, 2011.
https://lh6.googleusercontent.com/-w...2/IMG_5487.JPG

Being wet seems to reactivate the tannins that remain in the leather after it's been tanned; so as it dries on the last, the color already starts changing:
https://lh5.googleusercontent.com/-m...2/IMG_5492.JPG

Initially it dries pretty fast, but it takes a while for the last of the moisture to evaporate. As it dries, the color changes unevenly. I'm guessing this was somewhere around September 10.
https://lh6.googleusercontent.com/-i...2/IMG_5499.JPG

By October the saddle was in use on my commuter bike:
https://lh6.googleusercontent.com/-T...2/IMG_5522.JPG

About a half year later, I had to replace the rivets. I also embossed a design on the side:
https://lh6.googleusercontent.com/-6...0/IMG_6760.JPG

By now, several thousand miles later, the color is an even dark brown. I should take it outside and get a better photo, but this gives you the idea:
https://lh5.googleusercontent.com/-a...0/IMG_6761.JPG