NOTICE: The wiki has undergone updates and everything is running smoothly. I am still working on the CSS so there are a few minor visual kinks.

From JAWiki

Coloring text or names in the game is very simple.
In order to do this, just type a color code in front of the text you want to color.
Color codes are made out of 2 characters: a caret ('^') followed by a digit.

Valid color codes are:

^0 - Black
^1 - Red
^2 - Green
^3 - Yellow
^4 - Blue
^5 - Cyan
^6 - Purple
^7 - White

For example, to say "hello" in red, I would type "^1hello" instead.

While these color codes do work in chat and names, they do not show up properly in the console, so use their equivalants as shown above.

^8 - Black
^9 - Red