I purchased a Leviathan’s Eye of Agility on my 39 rogue and started to socket it in Golad, Twilight of Aspects. The gem shows +12 agility on the auction house and in my bags, but when attempting to socket it shows that it only provides +6 agility. It should be consistent in that it either shows only 6 agility for my character if that is all it will provide, or it should socket as the shown stat value of the item.
Edit: I also tried a Kraken’s Eye of Agility which shows +9 agility and only sockets to +4 agility. Quick Jewel Cluster shows +16 haste and only sockets to +4 haste. Same problem may affect a lot of other gems.