Patch 10.0.2 (2022-11-15): Stacks to 1000, up from 200.
Patch 6.0.2 (2014-10-14): Stacks to 200, up from 10.
Patch 2.1.0 (2007-05-22): Essences (Earth, Fire, Air, Water, Living) have had their drop rates significantly increased. Also Outland creatures that dropped motes will now have a chance of dropping essences as well.
Patch 1.3.0 (2005-03-07): Changed to good quality (green) to indicate their value and so that they are distributed properly by group loot.