This article lists all of the codes you can use with many plugins in Minecraft using Spigot or Bukkit. Each colour begins with a ‘&’ symbol followed by its letter or number, and the ‘§’ symbol is used in vanilla, listed as follows
&0 - Black
&1 - Navy / Dark Blue
&2 - Dark Green
&3 - Teal
&4 - Dark Red
&5 - Purple
&6 - Orange / Gold
&7 - Gray
&8 - Dark Gray
&9 - Blue
&A - Lime Green
&B - Light Blue
&C - Light Red
&D - Pink
&E - Yellow
&F - White
You can also use plugins to gain other codes, ones that can make your writing bold or italic and more. Each colour begins with a ‘&’ symbol followed by its letter, listed as follows
&M - Strike Through
&N - Underlined
&L - Bold
&K - Random
&i - Italic