The Serpent's Gems - NWN Side Quest (Chapter 2)
The Serpent's Gems is a side quest that begins in Port Llast by speaking with Elaith in the Alliance Arms Inn. You'll have to pass a Persuade check to accept this quest but it should not be too difficult since you'll get as many tries as you want. Upon starting this quest you'll be given Wanev's Cottage Key which can be used to enter Wanev's Cottage in Port Llast (optional).
For this quest you're tasked with hunting down 3 different gems which are held by 3 different people that you'll meet throughout Chapter 2. One gem can be obtained from Zamithra in the Green Griffon Inn, another can be obtained from Wanev in Wanev's Tower and the last one is found in Setara's House in the Heart of the Forest.
Zamithra's Gem: Zamithra is found in the Green Griffon Inn which is on a map named the same thing. You can reach this location by traveling straight north from Port Llast through the North Road until you get to this map. At first you'll find Zamithra on the 1st floor of this building but after talking to her here she'll go up to the 2nd floor which is where you'll get the Gem.
Setara's Gem: You can find Setara's Home on the Neverwinter Wood - Heart of the Forest map. It's located in the eastern most portion of this map, there will be a cave entrance here that leads you into her house.
Wanev's Gem: Wanev's Gem is found in Wanev's Tower, you can find the entrance to this tower in the southern portion of the South Road map. Behind Wanev on the 2nd floor you'll find a small dungeon, the gem we need is found inside of a chest in this dungeon.
Zamithra's Gem
You can find Zamithra on the 1st floor of the Green Griffon Inn (pictured above). Depending on your dialogue choices with her you may end up fighting her where she is standing or you'll have to follow her upstairs and fight her in her bedroom. If you fight her on the 1st floor all you need to do is loot her corpse for Zamithra's Gem.
Alternatively, if you fight her upstairs you'll have to loot the gem out of the chest. One thing to note is that when you go back downstairs you'll be ambushed by the rest of her guards left alive down here. Either way though the fight with her and her guards should be no problem.
Setara's Gem
The second gem for us to collect is Setara's Gem and as the name suggests you can get it from Setara. You can find Setara inside of her house which is located on the Neverwinter Wood - Heart of the Forest map. In order to reach this map you'll want to take the eastern exit out of Port Llast and travel east along the East Road map. You'll eventually come to the Neverwinter Woods map which you will want to continue traveling east through until eventually you arrive at Setara's Home.
Setara will start The Witch's Mirror side quest which is the peaceful way for you to get this gem from her. Completing this quest will also get you the key to free Bree for The Missing Druids side quest. Of course you also have the option of outright attacking Setara and taking both items from her. The option is yours!
Wanev's Gem
Last but not least Wanev's Gem is the last one that we need to obtain. You can find this gem in Wanev's Tower which is a dungeon that's located in the southern portion of the South Road map. Guarding the bridge to Wanev's Tower is Lerk the Troll; If you have Wanev's Wardstone from Wanev's Cottage in Port Llast then Lerk will let you past. Additionally, with the Wardstone you'll be able to enter through the front door.
Without the Wardstone you'll have to kill Lerk the Troll and enter Wanev's Tower through a cave which is to the west of the main entrance. Inside Wanev's Tower you'll find Wanev on the 2nd floor, he doesn't have the gem in his possession, instead you'll have to enter the small dungeon behind him and obtain the gem from a chest. For more information about this check out my Closing Wanev's Portal quest entry. This is an easy and short quest that Wanev gives to you that takes place in the same area you'll find Wanev's Gem.