title: How to handle different versions (Bourbon) of ruby gems on my Mac
body: <p>I installed the <a href="http://bourbon.io/" rel="nofollow">bourbon</a> gem on my OSX machine some weeks ago:</p>
  
  <pre><code>gem install bourbon
  </code></pre>
  
  <p>Now i have problems with bourbon in a web project (gulp says "mixins not found") so I wanted to uninstall and re-install the gem. So I typed:</p>
  
  <pre><code>$ gem uninstall bourbon
  </code></pre>
  
  <p>Surprisingly I get the following message in the terminal:</p>
  
  <pre><code>Select gem to uninstall:
  1. bourbon-4.2.6
  2. bourbon-5.0.0.beta.3
  3. bourbon-5.0.0.beta.4
  4. All versions
  </code></pre>
  
  <p>Hm? It seems that there are different versions of the gem installed and doing </p>
  
  <pre><code>bourbon install
  </code></pre>
  
  <p>in my project folder installs the latest beta (which lacks some SASS mixins I think). I thought when I install or update a gem that the older gems are deleted or overwritten. So how to handle this the best?</p>