Horse Color Genetics: Differentiating Shade and Actual Color Difference

On a genetics forum on Facebook, a lot of people often times get mixed up with the 'shade' of the color, and would like to call it something else, when genetically it is the same. But a lot of stumping happens when one horse is so dark or light it is easy to think they are a different color than they actually are.

For instance, one person posted a picture of a horse that was so dark red that it looked black. In fact, at first glance I thought the horse was black. Upon second glance, I had no idea. It looked a lot like the horse below.

Here are some options this horse could be; faded black, smoky black, or dark red. My vote is red on the horse above. That's pretty weird, right?

Same for the horse's below. They could almost be palomino, but they are actually red.

So now, I guess the question is, when does it matter? How do you know when it is one thing, but it looks another? Why do genetics matter if the horse doesn't actually look like what it's genetics are? 

To say the truth, most horses look like what their genetics are. There will always be slight exceptions, especially in the coat pattern tobiano. 

For tobiano, there are certain characteristics that they normally would have. They main one is white crossing over the back, but strangely, in minimal tobiano, it is the rule that is broken the most. Like the horse below looks tobiano to me, but the white does not cross over his back.

Back to the main question of shades; when do shades matter, and when should they be ignored?

To me, shades don't generally matter, unless they cause you to question the 'genetical' color. Like the first horse, who some might call black, but is actually red. There are certain colors in which the shade does matter. Like bay dun or dunskin (buckskin plus dun), the difference being that one carries the creme gene, the other does not. Their offspring could be totally different, but the only way to tell without testing is by the shade of tan.

Genetically, these two horses are different. Kind of weird, huh? The first one is bay dun (some might call it just dun), the second is dunskin. How do I know? The first one is more tan, the second is much more gold. The creme gene sort of enhances the dun color and makes it a lot more bright or metallic. The difference in offspring is that the first one can pass on dun, while the second could pass on creme, dun, or both.

One case that constantly gets on my nerves is when people ask whether their horse is sorrel or chestnut or red. That is one case in which it doesn't matter, unless it is extreme, like the first horse. Or another one: what shade of bay is my bay? Cherry, mahogany, or blood bay? Honestly, that is one of the most insignificant questions ever, when they almost look the same. The only time that one would matter was if the horse was dark bay, or seal bay or brown. Even then, there is only a slight genetic difference.

All that to say, there will always be a couple horses who break the rules, especially with paint, and some horses that continue to stump people. I have heard of paints who the owners tested for every single paint coat pattern there is, and each one came back negative. In those cases, they are unknown mutations of paint no one knows how to test for.