What kind of text encoding is this? (gist.github.com)

They appear to be a 4 byte wide utf-8 characters According to my hex editor the G character is F0 9D 99 B6 while the C is F0 9D 99 B2. Here are the characters: http://graphemica.com/%F0%9D%99%B6 http://graphemica.com/%F0%9D%99%B2