Here's a quote from Sam Kurinsky, and a link to the page where I found it.

I hasten to add two points:

1) I have realized for a long time that Jews were probably involved in glassmaking. This idea does not surprise me.

2) However, it is difficult for me to accept the notion that they were the only people practicing this art until Medieval times. Nor that any and all glass industries can be demonstrated to have derived from Jewish traditions.

So, while I was interested in Sam's ideas, I do not just accept them. And in my correspondence with him, when I named instances that were counter to his ideas, he usually side-stepped any discussion of these ideas. He even frankly said he didn't "believe" what I was telling him—even though it was based on reasonable archaeology.

JDA.