Used to own the Ruby,now own the Ruby 2. In a nutshell, the original Ruby, circa 1990 had an output of 0.2mv, while the Ruby 2 has 0.3mv. The Ruby 2 is a little more resolving and airy in the top end.
According to Garth the new Ruby 2 is a biig improvement over the previous model. I've heard all three versions, (owned two) and frankly there isn't a huge difference between them IMHO. Not really worth the difference in trade in/price.
Like many things in Hi-end, small differences are sometimes boosted through the roof for marketing purposes. Best advise is to listen for yourself and you'll hear through all the hype.
Nonetheless, the Ruby's are excellent cartridges.