Color consistency

Bryan,

  Take a look at  http://www.cree.com/products/pdf/XLampXM_B&L.pdf

This shows how Cree produce millions of LEDs and seperate them into BINS depending on their charachteristic spectrum and chromaticity. From these bin selections, they offer manufacturers groupings -- Bins of similar LEDs which when placed in the same assembly look similar. Naturally, the manufacturer charges more for tighter groups with lower numbers of Bins in the mix. Single reels of LEDs will always come from the same single Bin, but you can generally expect more then one bin in your grouping - so across a single delivery of multiple reels, you will get a slight variance in the LED appearance.

Alastair