here's a shot in the dark... what about a flat sheet of mica, like
I'm voting for Aerogel myself. It's transparent and a very good
Here's a fellow selling a big slab on ebay.
I don't know how high the bidding is going to go, I'm guessing a
couple hundred dollars.
It is rather fragile. It may work for soldering, but it might
shatter if you were to drop a hammer on it, so don't drop hammers on
it. People make fiberglass reinforced composite aerogel, but I lost
interest before trying to hunt down a supplier.
It is very pretty, but too soft and gritty to make jewelry, I think.
(I got to handle some a long time ago at a visitors center at a lab.)
Unless you made a protective cage.... hmmm... aerogem.com makes
little glass pendants with aerogel in them, but they are very boring.