Gems and Stars are what you use to buy things. The fastest way to get gems is to mine for them. When you first start Tunnel Town, Peck will tell you how to do so. The following types of gems are:
Diamond(white)To mine gems, place a bunny on it. The bunny will immediatly start to mine! Each type of gem gives you a certain limit on how much your bunny can mine. Once in a while, a gem will pop up above it. Collect it and you will get gems! When the bunny has mined the limit, it will read a book and wait for you to collect the gems. You can put one bunny on the sapphire, two one the emerald, three on the Ruby, and four on the Diamond. You can also get certain amounts of money by completing goals!