Boron Cantilever and Ruby Cantilever, Why Ruby?

Both Berylium and Boron are toxic, but in two very different doses. You actually do need a certain amount of Boron and you'll get that through apples, leafy greens, grains, certain level in drinking water and/or multivitamins. In large doses, it does get toxic.

Berylium is really only dangerous when airborne, so machine shop working with beryllium will have very strict safety policies and safety procedures. Otherwise, you'll be fine (unless you decided to chew on the beryllium cantilever, but that amount probably won't do you too much harm although you may want to have your head checked if you do chew on it)

One of these days I'd like to compare my SoundSmith rebuilt XX-2 (snapped cantilever, so replaced with SoundSmith's ruby) with an orginal boron cantilever XX-2.

I am interested in the difference in sound. I like the way the Benz wood sounds. Soundsmith must be very busy as I have had a difficult time getting in touch with them. Do anyt other cart manufacturers use Ruby cantilevers in their better cartridges? I noticed that Lyra and Benz both use Boron.

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

The Ruby catilevers ar synthetic. I guess that is the easy way to make perfect Ruby rods.
Usually Ruby cantilevers are short. ALA my Dynavector Ruby 23 And the even shorter diamond one in the Dynavector 17D3
(I own both Dynavectors)