I went to my local electronics store and asked for a powerful LED because I wanna make a small flashlight. They gave me this thing, but the problem is that the stores in my area don't have any datasheets or anything of the like. When I asked about the current or forward voltage they just told me they don't know and that I should try several resistors and stick to the one that doesn't burn the LED... (basically trial and error because they don't bother with that datasheet stuff...).
So... perhaps could somebody here give me an idea as to what kind of resistor I should use with this thing?
I am using 2 3-volt lithium batteries (CR2016) to provide 6 volts. The guys at the store know that the maximum voltage that the LED can withstand is 3V because they burned 2 LEDs in front of me when I asked about the voltage...
Here are the front and back views of this thing. The metal thingy is supposed to be a dissipator: