I've noted this in the blm forums before but i'll put it here as well.
I farmed my dark rings (and yesterday my refresh hairpin) on Black Mage/Scholar. And I had capped Amber, Pearl, and Azure (and some Ruby). By the time I was done I had capped Silver and 120ish Ebon.
This method requires Vidohunir, the mythic BLM WS. Also while building Amber, put away all your staves except your Aquilos/Varunas and the grip of your choice (I used Ossa Grip). This prevents you from losing TP to an accidental macro swap.
The order I do my lights are: 64-96 Ruby, cap Amber, get 130-160 pearl.
Then I go on a killing spree which obviously will cap Azure since i'm on blm.
For Amber and Ruby, I use Sea Daughter, Cosmos, and Beyond atmas. I go to where the Treants are and find the Ephemeral Limule that is roaming there. I hit it w/ Blizz V and Blizzard I or II until it's at 5% or so. By then I have regained TP and hit it with Retribution. As you may or may not know, Ephemeral Limules give either 16, 32, 64, or 128 Ruby if killed for Ruby. If I kill and get 128, I zone out and try again. 64 is the target amount, but up to 96 is fine. As long as I don't get 128 i'm fine.
Next I work on Treants and the Pavan that is also in the area. For Pavan, Blizz V usually one shots him, so I hit him with Blizzard IV and blizzard I if necessary. Since he tends to resist Vidohunir, I try to get him down to 2% before I use Vidohunir. Upon a successful amber kill you will get 16, 32, 64, or 128 Amber. For the Treants, just wait until you have about 80% TP then blast one with Blizzard V. If you get the Treant down to 25-30% HP, you should be able to kill it with Vidohunir for 16 Amber. Proceed until Amber is capped.
The reason I cap Amber is because since i'm going to be capping Azure anyway, I want the gold chests to appear at a decent rate. Also as mentioned before, the NQ pop items are replaced by KI and are of the same frequency. (Btw for those who don't know, every mob in Abyssea - Konschtat will give you azure)
Once Amber is capped I switch to normal BLM atmas - Minikin Monstrosity, Beyond, and Ultimate (ensuring I have RR up from my /sch subjob). Then I run around hunting VNM until have about 130 Pearl light. My kill method basically is pop, Blizzard V, Water, and melee it down. Once in a while i'll get a set proc and one shot it, but what can you do. Obviously i'm also opening up red pearl chests and ruby chests if i'm not up to the 64-96 ruby range.
After I reach the desired pearl count, I then begin my killing spree with forbidden keys in hand. I usually kill the puddings near Fistule because they take enhanced magic damage, can be aspir'd, and the fact they stop to cast is an advantage. Use Sublimation on /sch, and use Parsimony/Bliz V when the strategems are up. When you get an Intense Soothing Light blue chest, pop manafont and the chest for some free quick kills. If you're capped on xp (and who isn't nowadays), you can also pop ebon and silver chests. Use pearl from red chests to eventually cap out your pearl. Once my pearl was capped I actually popped an intense ruby chest to bring myself up to 140 ruby on my last farming session. Once you're at or past 128 ruby, all red chests are gold/silver/ebon. My logic is the red chests are going to drop from time to time anyway and as long as ruby is lower than amber/azure, they won't be too frequent. So why not have lights that can be actually useful (By eyeballing yesterday i'd say I got 1 red chest every 8 kills).
After about 3 hours worth of breaks (and 10 hours in the zone) yesterday, I walked out with 600k worth of dark rings/tower shields/phrygian ores, and a refresh hairpin. Previous farming sessions yielded me my 2 keeper dark rings - 1 with -6% PDT, -5% MDT, -3% BDT, and the other with -5% PDT, -6% MDT, -3% BDT. I also have 2 dark rings in my MH that have -6% PDT and -6% MDT respectively.
It's all luck of course. The best you can do is tailor your lights and kill speed and keep trying. The awesome augments do exist I promise.
99PLD 70WHM 99WAR 99BLM 49THF 17MNK 12BST 1DRG 49NIN 47SAM 49RDM 49SCH 21RNG 99BLU