Skill Gem Drop Rate.

I have completed the Campaign and 8 maps.

During the second half of Act 3 Cruel (After Matlan Waterway onwards) and through those 8 maps I have not had a single Skill gem drop. I have had one Lvl14 Spirit Gem drop. I had heaps of drops prior to that. I have 9 unsued Lvl13 Skill gems.

I have had to buy Lvl 14 and 15 gems to increase my skills since about Lvl60 to now Lvl71.

I have previously always been able to drop enough gems to keep my skill set up to level with my character.