Red Vases

I only ever heard that the red glass had gold in it. I think that cobalt blue glass gets its color from cobalt.
"Cobalt glass is a deep blue colored glass prepared by adding cobalt salts of alumina to the molten glass" http://en.wikipedia.org/wiki/Cobalt_glass

great vibrant colour....

I heard or read that the intensity of ruby red glass and cobalt blue glass is achieved by the amount of gold that is mixed in during the making of the glass...whatever, it's surely beautiful.