I know Herter's arrows were made of "Farbenglas". Un less someone wil lcorrect me here, it was made by Gordon Glass. They are identical to Gordon Glass arrows. It seems to me that the word "Farbenglas" was just a marketing ploy.
As far as the glass used in Bear bows, it is my understanding that Bear got a contract from Chevy to make the suspension springs in the Corvette out of the same glass that went into their later compound bows. Now I don't know if Bear actully manufactured the glass or they got the product from a third party such as Gordon, or whatever.
When it come to things like this, I have been known to be wrong on some very rare occasions. So if anyone wants to correct me here, I am open to be re-educated.