http://www.xbitlabs.com/news/cpu/dis...322034857.html
Step 5: Determine the color of the die.
Reddish from all angle of views - Average in overclocking, mostly can run at 2.0GHz (2400+) with 1.65v default voltage, but can perform better with higher Vcore.
Reddish with certain parts of reflective green area - Can either be very good or very bad. The lowest achievements were something like 2.0GHz (2400+) with 1.85v at least, or only 2200MHz with 1.65v.
Reddish core with reflective white under light - Awesome for overclockers. Can run at 2100MHz - 2250MHz using default voltage.