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.
Boron Cantilever and Ruby Cantilever, Why Ruby?
I have noticed that many of the better cartridges use Boron cantilevers. I know that Soundsmith uses a Ruby cantilever. I was thinkin of having my Benz Wood Body cartridge retipped but was not sure if the different material used for the cantilever will impact compliance and even sound. Why not boron like the original?