Here are the results of crafting Infernal Alchemist Stones on my alt that has alchemy. I had enough materials to craft 114. All of the materials I collected over time via World quests and dailies when I had the chance.
Infernal Alchemy Stones created: 135
http://imgur.com/a/QQZGO
Infernal Alchemy Stones Proc'd: 21
Rank 3 Proc Rate for this Session: 18.42 %
Obliterum Ash: 19,741
Average Ash per Trinket: 146.22
http://imgur.com/a/0my1b
Total Obliterum created: 197
0 Gold invest,it's just from playing on the account