The following information is only true if you have all 3 abyssites for each chest type.
128 of each light will cap each light. So, technically, you only "need" 128 amber to have a chance at getting a wivre hairpin with refresh. However, any lights over 128 also increase the frequency of that chest relative to your other lights. For instance, if you have 128 azure, and 128 amber, you'll see about the same of each (although amber chests seem to occur less than ruby and azure from my experience).
Now, since you want TE's I assume, as well as the wivre hairpin, the best combination of lights you can do is 128 azure/255 amber. Ruby should be avoided altogether. Treant saplings work great for that.
If you have BLU, I had no trouble going BLU/RDM and rounding up all the wivres. Then CFH on the one you are nuking, and you'll kill all the unclaimed ones and gain no additional azure lights. For some reason, disengaging from these mobs does not prevent you from gaining lights. If you don't have BLU, treant saplings are probably your best bet.
Edit: Highly recommend you build pearl off the VNMS. They give 10-15 guaranteed. With 3 abyssites you should only need around 115.
Edited, Aug 10th 2011 4:40pm by RangerMorie