WarmGlass.com

I don't remember if this was ever posted here but the re-post can't hurt. Very expensive equipment but some interesting techniques. I wouldn't try it with fused stuff though.
http://www.dump.com/glasscutting/

And I won't try it until I hit the lottery ...

interesting stuff. I apparently need to buy a tie before I make my next circle cut tho

I use a similar but different approach, utilizing slightly less expensive tools (like a $1 screw driver instead of their auto tapper, along with a propane torch to finish the starts). I'm pretty sure you could do this on a transparent fused slab with no interior bubbles, that is sufficiently annealed. However the process is really all about clear float glass. I have to admit that my skillset is up to 12mm glass. I can't afford to do the learning curve for 19mm. The big skill you need to acquire is to get the edges 90º, and not flared. I once tried cutting a straight line on 36mm fused clear float glass with my cutter and a framing hammer. I was shocked when it worked.

Cheryl, I have seen pictures of guys in white shirts, ties, and aprons making leaded glass windows, including lamp blacking the putty. I think those photos were in the first half of the 20th century.