ERROR: Could not find a valid gem 'sass' (>= 0), here is why: Unable to download data from http://rubygems.org/ - Errno::EACCES: Per mission denied - connect(2) (http://rubygems.org/latest_specs.4.8.gz)
This is work for me. Try this...
gem source -a http://rubygems.org/
answer y to the question "Do you want to add this insecure source?"
then you can use command...
gem install sass
http://*.com/questions/16136006/install-sass-using-gem-on-windows-8