I have bunch of gems on my computer that I want to use in a chef recipe.
I know it is possible to put them in a directory like /tmp/gems and just:
gem install *.gem
You can add local directories to your Gemfile (example from the docs):
gem "nokogiri", :path => "~/sw/gems/nokogiri"
Alternatively, you can set up a local Git repository with the gems in it and write a Gemfile like this:
gem "gem1", :git => "file:///tmp/gems", :branch => "gem1"