The surface of glass is smearing some metal or metal oxides film like gold, silver, aluminum, chromium, nickel, iron.  

Reflective glass has higher heat reflective rate. For example, the reflective rate of 6mm float glass is only 16%. On the same condition, the reflective rate of antisolar glass has 40%; and the rate of reflective glass is 61%. So it is processing to insulating glass or laminated glass to increase the heat-insulating property. The metallic film reflective glass homomallous imaging. That is say, in the day time, we can see the outside scenery through the glass on indoors, but cant see the room outside.