i've noticed you can look at the led itself; if there are 3 little wires connected to the die (2 on one side, 1 on the other side), then it's a CE, if there are four little wires connected to the die, then it's a Q5. it's been consistent like that for me at least.
Same here, my Premium Q5 has four conductors and my P3D-CE only has three.
I have to disagree with Marduke, as the practical difference between the 215 lumen Premium Q5 and 160-lumen P3D-CE is substantial.
My P3D Premium Q5 has "Premium Q5" stamped in the head and my P3D-CE has no markings on the head.
Keep in mind that there are four versions of the P3D;
215-lumen P3D Premium Q5 - Premium (Q5) Cree 7090 XR-E LED
200-lumen P3D Premium 100 - Premium (100) Luxeon Rebel LED
160 lumen P3D Rebel 80 - Luxeon Rebel LED
160-lumen P3D CE - Cree 7090 XR-E LED
If all else fails, read the specifications on its original retail carton.