what is hotter, a white, blue, or red flame?

If the element on your stove had no limit, it would theoretically pass from the original black(emitting no heat) to red (925), orange, yellow and then to white(1200) and finally bluish white (2000).

The hotter the temperature, the more the colours shift from red to yellow to white to blue.

Blue is so hot it is at the very edge of the visible spectrum. Beyond blue are ultraviolet rays, which can cause burns and even skin cancer

(source from READER'S DIGEST JUNE 2004)