FuhriousThe ruby is higher than ceramic on the mohs hardness scale so in in theory it would spin longer/smoother. In reality you won't see a performance difference with a ruby vs. ceramic. The difference is the bling factor, a ruby bearing looks awsome against the stainless steel.
The downside with a ruby is it can break a lot easier than ceramic. It is durable and under normal use there's no issue but if dropped by accident it will break where a ceramic wouldn't (same height drop).
I have this exact top with a ruby and love it, great quality - especially at this price point. That being said almost all my other tops (around 40 or so) have ceramic bearings. Generally I go with ceramic with the more expensive tops but at this price it was worth the risk to me to go for the ruby. I've spun the "bleep" out of it with zero issue's and no regrets.