Take a look at the following post and the comments that follow:
It looks like @pmusaraj is going to be working on something that will end up being exactly what you are looking for, but in the mean time he provides instructions for using svg-uri().
Edit: The Github link in the above post appears to be broken. This should be the current working link:
Once you’ve clicked on that link, then click on the appropriate set (solid in your case), then click the raw button and search the page for check-circle. The code below should be what you need, but I wanted to include instructions for posterity.
<path d="M504 256c0 136.967-111.033 248-248 248S8 392.967 8 256 119.033 8 256 8s248 111.033 248 248zM227.314 387.314l184-184c6.248-6.248 6.248-16.379 0-22.627l-22.627-22.627c-6.248-6.249-16.379-6.249-22.628 0L216 308.118l-70.059-70.059c-6.248-6.248-16.379-6.248-22.628 0l-22.627 22.627c-6.248 6.248-6.248 16.379 0 22.627l104 104c6.249 6.249 16.379 6.249 22.628.001z"></path>
The rest of the instructions are still accurate.