I tempered my first knife a day ago at about 400 degrees( my toaster oven only goes by hundreds of degrees). I put it in the oven and left it there for two hours. When i pulled it out it came out looking like a rainbow.What did i do wrong? I've spent some time thinking about it and i've come up with a few ideas as to why that happened. I put the knife in the oven diagonally because that was the only way it would fit, the middle of the knife turned blue right where that knife rested, above the heating element, on the rack.The blue is interrupted by a bronze strip exactly where the knife rested above the heating element. The reason i'm wondering what happened is because i thought at 400 degrees the whole knife would take on a straw color not any other color let alone a rainbow of most of the oxidation colors. Can anyone help me understand what happened? Should i continue with another tempering cycle, or should i start over and re-harden the blade and try again?