title: how to change Angular 6 material radio button outer ripple color
body: <p>I wanted to change Angular Material Radio button default color. I can only able to change to radio button color. </p>
  
  <pre><code>&lt;mat-radio-group&gt;
    &lt;mat-radio-button value="1"&gt;Option 1&lt;/mat-radio-button&gt;
    &lt;mat-radio-button value="2"&gt;Option 2&lt;/mat-radio-button&gt;
  &lt;/mat-radio-group&gt;
  </code></pre>
  
  <p>But I can't able to change outer ripple effect color when we click option. Some one please help me to solve this. </p>
  
  <p><a href="https://i.stack.imgur.com/BCmlb.png" rel="noreferrer"><img src="https://i.stack.imgur.com/BCmlb.png" alt="enter image description here"></a></p>