Well, Online's Rubin red is a bright red. It stands up off of the page with a vibrancy that you can't miss.
It does have a bit of dotting on cheaper papers, but I used it to grade some student papers this last semester, and it was totally usable.
If you can find any of this ink, snap it up. I haven't found an online source for it since the Goulet's stopped carrying it. I only got samples, and I regret it. The three inks that I've tried from them have been really excellent inks. This is my favorite so far.
I had several reds inked up at the time. I'm actually still using Grenade and Matador right now. I need to write up the reviews for those inks, but I haven't gotten to it quite yet. Soon, though. Soon.
Here's the water test for this ink. I also show off the pen that I used for the review in this video. It's a Laban PF-900 that my wife surprised me with a few months ago. I had a little problem with the section of that pen, but that's a story for another day.