The gem worth 2k is a malachite gem, which are in limited supply. They are required for all level 10 enchantments, and any level of the healing aura enchantment. In D2:ED the effect for level 9 enchantments was almost the same as level 10, so I stuck to level 9, except for healing auras (where I only used level 10). I found 28 total, including reloading at malachite veins, so selling one or two shouldn't be a problem, though the enchantment effects were increased in DKS, and there may be a larger difference between level 9 and 10.

The following malachite gem section of the D2:ED walkthrough is valid for DKS, and in the FoV part of the game there are additional sources.
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| Malachite Gems |
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Needed for the best enchants in the game, these rare and elusive gems are
quite precious. While it's near impossible to get all of them in a single play
through of the game, using this list, you should be able to get enough to
comfortably enhance your favorite weapons, armor, and jewelry.

Broken Valley:
-You can buy two gems from Merchant Lamotte in the Broken Valley village.

-The only other gem you can acquire before adventuring in Orobas Fjords comes
from waking up the sleeping trio east of Lovis' tower.

Orobas Fjords:
-On the path leading to High Hall from the Depleted Ore Mine, you encounter a
traveling merchant by the name of Carleton. He sells a malachite gem, but be
careful! At the time of this writing, there is a bug that causes you to be
unable to buy from him if you open trade via dialogue. Click the Trade button
instead and you will be able to buy the gem.

-You receive two malachite gems as a reward for completing the quest 'The
Horror of High Hall'. If you read Beatrice's mind, the reward becomes four
gems, making this the single largest (reliable) source of malachite gems.

-If you read the goblin Charlie's mind while on the quest 'Reaping the Seeds',
a small treasure chest appears in the nest on top of Yggdrasil, and a
malachite gem is inside.

-If you chose Radcliff as your enchanter, you can trade the gem he asks for to
a pair of goblins in exchange for two malachite gems. Doing so will bar you
from ever getting a second upgrade for your workshop, but it's probably worth
the trade off unless you enchant a whole lot and hate utilizing your runners.

Malachite Veins:
The rest of the malachite gems can be found randomly in malachite veins. There
aren't many, and each one isn't guaranteed to have even one gem (though forum
rumors suggest up to four in a single vein). If you save your game before
approaching any given malachite vein, you can always reload until you get more
gems. However, it's probably not worth reloading as long as you get at least
one.

-The first malachite vein you're likely to encounter is in the Depleted Ore
Mine, just past the three pedestals with the red, blue, and dark books on top.

-There is a second vein just behind the first. After you finish plundering the
first, turn around and look up. You'll have to jump onto a rock to reach it.

-There are two malachite veins near the Patriarch. The first is along the
eastern wall and is relatively easy to find. The second is hidden behind some
rocks on the western wall, very near an empty wagon sitting just in front of
the wooden platform you stand on when talking with the Patriarch.

-Two more malachite veins are in the Lost Tomb (the cave opened by the four
treasure hunter's seals). The first is along the right wall as you approach
the stone platform. The second is beneath the wooden platform on the left.
...and those poor adventurers thought there was nothing of value in there.

-There are two malachite veins in the Well Cave, in the room where you fight
Zagan. It's relatively hard to get these without triggering the combat, after
which it's technically possible to still get the gems but rather difficult.
Simply hug the left wall as tightly as you can, jumping up onto tall rocks
instead of going around when possible. When you're directly south of the large
orb in the middle of the room, you should see a large, flat rock with two
malachite veins on it. If you activate the combat by mistake, it's easiest to
just reload.

-If you don't want to or can't reload, you'll have to exploit a bug to get
the above two veins. First, finish the combat and fly to the exit. Then, after
transforming out of your dragon form, turn around and walk onto the large rock
to the left. You'll want to jump out into the cavern, but angled sharply to
the right. If done correctly, when the game tries to auto-transform you into a
dragon, you'll get a "not enough room" error and fall into the lava, strangely
taking no damage. From there, you should jump out of the lava, work your way
around the orb with skillful acrobatics, and finally claim your gems. It's a
lot easier to just reload.