I really like the new Jabos and my son is downright CRAZY about them, so we have many. I don't know much about glass, but I do like to learn, and I find it sad that any serious or critical discussion of these marbles is near impossible. I think that oldmarblenut's initial message may have been a bit alarmist, and could probably have been worded better, but I think his premise is not unreasonable. With all of the great color and additive combos that have been produced, it seems reasonable that COE might be a concern. And I am sort of surprised that nobody involved in the production of these marbles has yet addressed his point. It's seems pretty simple to me . . . Was any testing done, or was COE considered when purchasing or combining the glass for these marbles? No dissing, no accusations, no alarm - just a question. -Ric