Could not verify the SSL certificate for https://rubygems.org/
I had this problem on Mac OS X Yosemite with ruby 2.3.1.I fixed the problem by downloading http://curl.haxx.se/ca/cacert.pem to /usr/local/etc/openssl/
and adding this line export SSL_CERT_FILE=/usr/local/etc/openssl/cacert.pem to .bash_profile
Credit to Can't run Ruby 2.2.3 with RVM on OSX but it was hard to google the right answer, so added to this page.
The solution for me on OS X 10.9.5 was to sudo rvm osx-ssl-certs update all.
Source: http://jacopretorius.net/2013/10/could-not-verify-the-ssl-certificate-for-rubygems.html