Had the same problem.
They nerfed it so bad. I haven't gotten 1 single emerald from a wyvern in my entire playthrough. I have moderate luck too, once I killed a ashen warlord and got an AotD and the staff thing.Had the same problem.
I think the drop rate of emeralds from wyverns was lowered in one of recent updates. Go to Mercian Royal Crypt instead, one run gives you about 1-3 emeralds from sarcophagi. Or try vorators nests in Cave of Echoes (Thyr Mountains), chances of emeralds lower, but you will have plenty of vorators eggs for making omelettes (very useful for long dungeons such as Sewer of Horrors).
And some hint: save/load outside of dungeon will reset it, so you don't need to rest in town. Works with any other areas also.
I got 1 emerald from them and if I remember correct it was wyvern whelp. Earth elementals have decent drop rate of emeralds, but there are no such places where you can find them in large enough groups.They nerfed it so bad. I haven't gotten 1 single emerald from a wyvern in my entire playthrough.
Glorious isn't it?Such a pity, when I found out that large emeralds needed for crafting by minotaurs I already sold a bunch of it to Orduc in Jabal