If you use MacPorts, the following should get Ruby installed and working on your machine.

Install RVM

Taken from the RVM website:

curl -L https://get.rvm.io | bash -s stable --ruby

Install OpenSSL and libyaml

sudo port install openssl libyaml

(Re)Install Ruby

rvm reinstall 1.9.3 --with-openssl-dir=/opt/local --with-opt-dir=/opt/local