Gold like glass?
I've always thought this description it was odd: Revelation 21:18 ESV "The wall was built of jasper, while the city was pure gold, like clear glass." http://bible.com/59/rev.21.18.esv But maybe the Romans understood the concept. And if this kind of cup was used to detect purity – or warn of impurities that are present in what it contains – then the whole metaphor starts to get really interesting: http://blogs.transparent.com/latin/ancient-roman-nanotechnology-improving-the-future/ Just an idea; not going to start a new denomination over it. :)