@elliottbnewcombjr
Thanks for that!
Yes, ruby is the same as sapphire except for the red colour which is caused by traces of chromium. Sapphires can be every other colour except red. Chemically they are aluminium oxide, a compound made from a couple of the most plentiful elements on this planet. Aluminium oxide is very hard, and saphhires are used for scratch resistant watch faces. It is widely used in the abrasive papers known as carborundum.
Boron is a very light metalloid, number 5 in the atomic table, so all other things being equal (they never are!) it should be the best for trackability. While all these options are hard, they are also brittle, so I settled for an aluminium cantilever in my Audio Technica cartridge.
The background is that I inherited a Garrard 301 turntable with an SME tonearm (fixed headshell) and Shure V15 cartridge. I could buy a brand new Audio Technica VM540ML cartridge for less than just the Jico replacement stylus, so I did.
When a low price Jico appeared on ebay I thought it was worth a try despite swapping cartridges being a royal pain with the fixed headshell tonearm. I am slowly improving the sound quality from the Garrard, so I don’t mind spending a bit more on it! Trying to discover why they have such a following ...