Goldstone is a little-known gemstone that was speculated to have been discovered during the Renaissance by glass-manufacturing monks in Venice when molten copper was accidentally spilled into molten glass. Hence goldstone has an alternative appelation of monk's stone or monkstone.
When the molten mixture of glass and copper cools, the copper crystalises which creates the impression of a reddish-brown stone with a golden starry-glitter. The night-time constellation effect of goldstone lends it another of its alternate names: stellaria.
The reddish-brown hue of the stone is actually an illusion. The glass itself is transparent and is given the appearance of reddish-brown by the copper crystals.
Goldstone can also be found in blue, which is paradoxically known as blue goldstone.And there is green goldstone too
http://en.wikipedia.org/wiki/Goldstone_%28gemstone%29I have a goldstone sphere like this one it's 31/2 inches diameter Got it at a gem show.It looks like a night sky full of sparking stars.
This is what green goldstone looks like.