This article gives the boiling points for different metals. They are all pretty high, which would no doubt make them toxic, in addition to any chemical reactions they would cause. According to the chart, the boiling point for gold is 5072 degrees F, 2800 degrees C. I could not find any reference to what color, if any, that these metals would have in gaseous form. Here is a Wikipedia article on the toxicity of metals.

Pure gold is not toxic. So gaseous gold is not toxic, but if you breathed it or put your hand or arm into it, you would be dead from severe burns.

Gold is a metal and metals don’t go into microwave ovens because the metal would probably just reflect the microwaves off and around. Gold would have to be melted in a furnace of some type, probably natural gas fueled.