Are Glass Chalices Permitted?

[Confiteor]

buffalo:

Again I will post this. Note the word reprobated. Whoever knows Latin will also know the absoluteness of the bold statement. I cannot see how this is arguable. Also, did Chicago approve crystal before or after RS?

I had the same question–don’t the US bishops have to follow these instructions? Because I don’t think any of them “implemented immediately” or even yet in many cases. Also, is there really a difference in “glass” and “crystal”? Isn’t crystal essentially a higher quality glass? Are they actually made of different substances?