Apple included cute little emoji that bounce around and bring life to the otherwise mundane staples of online communication on the Apple Watch. When you're selecting which emoji to send, you can use digital crown to scroll through the various hearts, faces or hands to pick the best response for the given situation.
Only, the default colors may not best fit your mood. For example, when you're mad sending a red-faced emoji is much better than the standard yellow affair. Right?
The next time you select the option to send an emoji, you can change the color of the respective icon by pressing on the screen of your watch (otherwise known as Force Touch). A quick press, and the color is changed. Another quick press and it changes again.
Examples of the colors for the face emoji:
Examples of the colors for the heart emoji:
The hand, for some reason, is limited to the white glove treatment -- in other words, you can't change its color.
Unfortunately right now, as you can see, the color options are limited. But hey, it's a start.