HI Steve,
what you have to do, is to find an Antiques market/fair/shop in your area, walk around, pick up
the glass , handle it, you will soon notice the difference in quality and feel.
Charity shops are full of other peoples clear outs, not, that occasionally you may get a nice piece,
but its 1 in a thousand!
This piece is a very poor copy/imitation of cut to clear/ flashed/ overlaid glass,
keep reading books, websites, ebay, and all the posts on here, it may take a few years!
it did me, and i feel ive only scratched the surface!
be patient, you will find the answers you seek! ( i think thats a star wars quote!

)
Andy