1, color (appearance dao), visual du observation.

If you're looking for a way to get a good deal on your own, it's important to know what you're looking for.

Copper's capacity words are a little partial red and purple.

2, density.

The density of different kinds of different.

3, the nature of different.

In the fire roast (do not use candles to roast), blackened copper is plated, black material is copper oxide. Did not change color is gold-plated, real gold is not afraid of fire.

Gold plating, is a decorative process, is also one of the common vocabulary. Initially, it refers to the surface of the object plated with a thin layer of gold. Later, it was also used as a metaphor for a person going to a certain environment for further study or exercise just to get a false name.