Take your icon game to the next level. Check out Fonticons, from the maker of Font Awesome.
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Font Awesome
             

fa-cc-amex · Unicode: f1f3 · Created: v4.2 · Categories: Brand Icons, Payment Icons

After you get up and running, you can place Font Awesome icons just about anywhere with the <i> tag:

fa-cc-amex 
<i class="fa fa-cc-amex"></i>

Looking for more? Check out the examples.