i loled at the guy who runned heroic 25 times for this ring, if you read thottbot right, you can see that this item ONLY drops on normal mode. so for all you healers out there: don't waste your time on the hard heroic version, go normal instead.

also if you look at the heroic drops you can see the item levels are 125 and the epics that drop on normal mode are item level 110 
so as you see the ring cannot and will not drop on heroic mode.

i hope this answered many of your questions about drop rates on normal and heroic mode.

Fixation Horde Ragnaros