Rubygems has at least one public mirror: http://stackoverflow.com/a/17150536/437888
There are also solutions such as https://github.com/pusewicz/rubygems-proxy allowing you to cache / proxy to rubygems.org
There are also solutions such as https://github.com/pusewicz/rubygems-proxy allowing you to cache / proxy to rubygems.org
There is also http://gems.gzruby.org/ if you happen to be behind the Great Firewall of China