I like inks. I like red inks. My favorite ink color by far is Diamine's Oxblood. And at the same time red can be disappointing and frustrating. It is often brownish and in that case no competition for Oxblood, with the possible exception of P.W. Akkerman's Stone Red (Dutch masters series). Or the red is too pink (Bishamonten), too orange (Esenin), or simply too light (Rouge Caroubier). What I miss is a dark, but bright, saturated red.
Lamy's Crystal Edition Ruby looked promising in the store, in a great bottle and reasonably priced. In reality, Lamy Ruby is a decent, mediocre red. Not very saturated, but really red. I wouldn't use it in the office unless you have to grade or correct. Personal notes or correspondence? Only when short, the color is not bad, but not pleasant enough for the eyes for longer reads.
Decent is also the word I'd use to describe its behavior. Writing gives a dry feeling, lubrication could be better. There is no feathering, shading is low to moderate, hardly any show-through, and drying time is much faster than average, around 13 seconds on crown mill paper. When you spill water, you'll probably want to rewrite, but it remains legible.
Comparisons with a few other inks show that Ruby comes close to Herbin's Rouge Opera (although that one is even less saturated) and is a bit brighter and lighter than Diamine's Monaco Red or GvFC's Garnet Red. The last two have a noticeable hint of brown in it.
To conclude, Ruby is not a bad ink, but not a great ink either. It scores average on most aspects. And no, it's not that dark bright red I'm still missing.
N.B. Paper used is Original Crown Mill Vellum (off-white)