Is it a part of old glass coaster?

[kuna12]

I found this piece of red sea-glass, and thought it might be a bottom of an old bottle. But looking at the reverse side, it's pretty clear that it's not any kind of bottom, it was always this flat - a coaster, perhaps? Can't find anything like this in Google Images (it usually works).

It's broken, but I think the embossing reads: DIAMOND, Diamond Heat Resistant Glass (inside the diamond), and word FOR. But for what? Please, help - I'm very curious to find out. Thank you!

 

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[dozer dan]

It could be something as simple a a pot minder. You put it in a pan of spaghetti or other cooking stuff and it keeps it from boiling over. They were made of tempered glass

 

[Vermont treasure hunter]

Could be a top to canning jar or mason jar. I have a bunch but none of them are red.

 

[kuna12]

Could be. But that Heat Resistant is confusing. What jar needs heat-resistant cap?

 

[kuna12]

That might be. I'll try to find - maybe there is a pic of it somewhere on the net.

 

[ARC]

Diamond Glass Company, Royersford, PA.

 

[kuna12]

I kind of thought so too, but their mark was simple small diamond, with no writings inside. Here is pretty big diamond with 'Diamond Heat Resistant Glass' written inside. Is it related to them or no, I'm not sure.

 

[xaos]

I am thinking perhaps a glass teapot...

 

[kuna12]

:/ That quote is horrendous, even if true.
The closest thing I found to this glass is Kopp heat resisting (not heat resistant) glass lens, but the lens is convex, what I found is totally flat.

 

[dozer dan]

:/ That quote is horrendous, even if true.
The closest thing I found to this glass is Kopp heat resisting (not heat resistant) glass lens, but the lens is convex, what I found is totally flat.
View attachment 1905739

I was wondering a couple days ago if it may be a viewing window of sorts from a furnace or smelter so you could tell at a glance that the fire was lit.

 

[kuna12]

Yes, that looks very possible, thank you!