The photos below show the same dog as a puppy, at 7 1/2 months and then as an adult. You can see how it changed from having the coloration of a tri to that of a sable. This is actually Sooner (one of our retired males). Boy were we surprised when he turned out to be a sable.
In the second photo you can see how the black is starting to disappear off his hind quarters, just above his underside, and off the top of his head. Even though his coloring changed he still turned out to be a beautiful dog.