Square Pan for Omelet

This is one of my favorite kitchen tools. This pan is used for cooking an omelet which is formed to a rectangle with the square shape. The body is made of copper, and it helps cook fluffy and delicious omelets because the metal conducts heat quickly and equally to the egg by its high thermal conductivity.
The original body color is shining copper, but when you use it on a gas stove, fires make pink and violet marks looking like a flower. As you use the pan, it is getting black and the flower is disappearing.