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Drop from red eyed assassin guarding the giant bolt canon defending smouldering lake.
another good place to farm sharp gems is in the corvian settlement. corvian knights drop them. knights are normally a pain, but are affected by rapport so use this on them and have your way with 'em.
So, the corvian settlement is by far the better place to farm these gems than the catacombs. I got 3 gems in the catacombs after about 30 min farming there. In corvian settlement I killed the corvian knight with the rapier, who is near the bonfire. I got 6/14 gems, it cost me about 15 min. It's harder, but a lot faster. I equipped a sharp ifused lothric knight sword +10 and stacked as much poise as I could. I had in both places an item discovery of 423. Good luck farming.
Sharp is actually better than refined or strength in a lot of cases now like if you have minimum requirements for strength to weird the zwiehander but 75 dex and sharp infuse it gets 30+ ar when the reverse is done but with a heavy infusion also a broadsword at 20/75 str/dex with sharp infusion it gets 478 ar
The greataxe hollows in HWOL drop raw gems, not sharp ones
Can someone add that you can use hidden body + Slumbercrest ring/Spook to just walk up to the crystal lizard and spawn at it from Dilapitated bridge?
If you run fast enough you can catch it.
those greataxe wielding undead in High Wall of Lothric dropped a raw gem, not sure about a sharp.. soo far nothing.
It dropt from red-eyed skeleton mobs BUT only after 15 mins of farming with 290 item discovery ( seal of avarice + 40 luck + golden serpeant ring ). It is an ultra rare drop indeed.
sharp infused causes adding dex from 60-75 to add around 2-3 ar per dex for most if not all infusable pure quality weapons such as the longsword,lothric knight greatsword,greatsword,greatlance,lucerene,halberd and caestus
In testing this I have found for many of these weapons leveling minimum str and going 40 dex actually strangely provides more AR than 40/40 refined