From the site at Visionofsages.com
>Make sure that nobody has camped this spot for about 30 minutes or so, to restart the encounter
Go to the Deep Sands Zone. It's located at 15k, 50k Notos, deep down. You can have the battlegroup stay at the surface and only send one person down to get the target.
The event will not happen unless there are 4-6 hammerheads around the area. Then, you will see a broadcast message indicating you that the sharks go into a frenzy, and one dives down to the sand to pick up the gem.
We sent a nightshade down to watch for the shark with the glow in his mouth, he had the shark targetted, and a ranger assisted the nightshade. The rest of the battlegroup stayed at the surface. There were a few broadcast messages before the ranger pulled, because we were waiting for people to show up, but the ranger pulled the one the NS had gotten for her. We killed the shark, and the ruby dropped.
- summarized from Bravest post and info from Mura
Tips:
When you enter Deep Sands, the encounter is triggered. An azure shark will enter and be attacked by the hammerheads. A "feeding frenzy" commences. During the frenzy, the sharks will ignore you even if you swim among them.
When the azure dies, he drops the ruby and one of the hammerheads picks it up. You should see a message that one of them picked something up out of the sand. You should also see an intermittant faint red glow around one of the shark's head. That's the one with the ruby. Kill it and it drops the ruby into someone's inventory.
The problems with this encounter are (1) it's very hard to see the glow, (2) you may not get the message that a shark has picked up the ruby if you're too far away and (3) if you use bleed styles, all the sharks will attack.
Everyone should stay close to the surface and one person (a stealther) should go down during the frenzy and try to see which shark picks up the ruby; pull the shark and swim back up for the rest to kill him.
The thing they leave out though, is MAKE SURE SOMEONE IS STILL IN BLOODMAR FROM THE BATTLEGROUP. We did this 5 folks and had the healers healing from bloodmar and the fighters who were getting bled from the shark bite, up near surface. That worked. When we killed hte shark from outside the area (all of us) we got no xp and no kill credit and no ruby.