How to play Undermine

About Undermine, from BoardGameGeek:

Garden gnomes have a secret life. Unbeknownst to you, the gnomes are mining your yard for gems! And, all this time you thought you had a gopher problem! Your goal in the game is to collect as many sets of gems as you can in this cute and fanciful mining game. You'll start out by setting up a mess of cards in the center of the table, that will be made up of gems and mushrooms. These cards will act as the "mine". Each player will then take turns building tunnels through the mine collecting gems and mushrooms. Gems can be sold through-out the game to get more tunnels and other tools. Mushrooms can only be used at the end of the game as to expand the size of gem sets that you can score. Sets must be made of all the same type of gem/mushroom, or all different ones. The bigger the set you collect, the more the set is worth. The game ends once any Gnome has 50 money, or any Gnome is out of tunnel segments they can build. The Gnome that has the most money at the end of the game is the winner! -description from the designer