With the data from both the first and second points, I'm now certain that the crystal is at the top of the Ruins of Farahlon to the northeast.
Unfortunately, the data indicates that the crystal is moving, which means that it has already been discovered, probably by the Burning Legion!
Just in case, I recommend that you take some friends along.
Slay the demon that has the crystal and return it to Nexus-Prince Haramad.
After this quest is completed, Ambassador Solannas and two honor guards arrive to confront Haramad.
Ambassador Solannas says: Indeed, Nexus-Prince Haramad, you do have much to think on. Such as turning that ata'mal crystal over to my master, Prince Kael'thas.
Image of Nexus-Prince Haramad says: No, I think not. The selflessness that I have just been witness to has cleared my mind. My dealings with your master are at an end. You may return and let him know that I have decided to turn the ata'mal crystal over to the naaru.
Ambassador Solannas says: WHAT! This is outrageous! You will pay for this, Haramad! You and your assistant here!
<Solannas and his honor guards attack the player.>
Image of Nexus-Prince Haramad says: Guards! Hold on, I will be right there!
<Haramad emerges from a nearby teleporter and proceeds to kill Solannas and his honor guards.>
Nexus-Prince Haramad says: That definately ended our business relationship with Kael'thas. Please stay here. I will return shortly and there is something I want you to do.