Boron Cantilever and Ruby Cantilever, Why Ruby?

Ruby is just a red Saphire. I am sure they use synthetic Corundum why not the blue or yellow??

There is the old notion of 'connotation' and the more modern one of the 'emotional meaning'. This may explain the association with jewels . No harm is done with Peter's Ruby cantilevers considering the price but think of those + 10 K Koetsus 'tuned' in synthetic precious stones. However even if those are 'real' or 'natural' one should never try to sell them as separate merchandise.
Elizabeth, those Dyna 'diamonds' are those also, uh, not real?

Changing from a beryllium cantilever on the stock V15VxMR to a solid boron rod with the JICO SAS replacement stylus drastically changed the tonality of the cart. The original sounded rolled off in the high end while the SAS made it closer to neutral, but still is subtly bright (comparisons were made with vinyl that had a CD counterpart released at the same time). So... it can't be stressed enough that changing any part of a cartridge will potentially change the tone in a fundamental way.

Lewm, Beryllium has an atomic number of 4, Boron 5; hardly qualifies either as "heavy" metals. As to the toxicity of Boron compounds, borax is used as a detergent booster and boric acid as an eye wash and a "safe" insecticide.