Boron Cantilever and Ruby Cantilever, Why Ruby?

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.

Sorry, John,and anyone else. I did not check the periodic table or even think hard before calling them heavy metals. My bad. Your point about the relative lack of toxicity of Boron (at least in ionic form) was exactly what I was inferring to begin with.

I'm getting sick reading this...maybe I'm having a boron or Beryllium reaction to too many LPs being spun....

With respect to Be, its the oxide(s) that are toxic. For years and years the electronics industry commonly used BeCu (Be copper) alloys in connector pins and relay contacts. But, as with lead (solder), our big brother EPA and other regulatory agencies have decided to ban its use for "our own protection".

Boron is a very common environmental element, and its oxides are harmless for the most part (boraxes). If you measure the composition of "dust" particles, you will find boron as one of the major components besides silicon dioxide. So your are breathing these Boron containing particles in whether you realize it or not.

I am amazed they are using sapphire (ruby) or even diamond as a cantalever material. Besides the cost, these are very brittle and fragile materials.

Berylium is toxic if it is inhaled only. Thus you can have Be tweeters and so on because the Be does not become airborne.
Dhl93... I used to work in the Jewelry business and have a GG. Niether Saphire or Diamond as a crystal is particularly " very brittle and fragile." How many Diamond rings have you seen break apart? Diamond cantilevers must be the crystaline form to be called "Diamond" otherwise it is just carbon.