Online:Heist: Glittering Grotto

Quick Walkthrough
# Talk to Fa'ren-dar and travel to the Glittering Grotto.
# Find seven pouches of  .
# (Optional) Complete the heist within 8 minutes.
# Return to Fa'ren-dar at the entrance.
# Return to the Thieves Den and talk to Fa'ren-dar.

Detailed Walkthrough
Read the Heist Board next to Fa'ren-dar in the Thieves Den. There is a new message, reading:
:"My sources say Glittering Grotto has a little more shine today. Rare gems, kept on site, not yet accounted for. Our buyer would like them to disappear without security being unnecessarily compromised."

Speak to Fa'ren-dar to travel to the Glittering Grotto and to ask more about the place itself: 
:;Glittering Grotto doesn't sound so bad. Nice even.
:''"It is a beautiful place, but don't let the gleam distract you from the dangers within. The lush overgrowth makes it ideal for traps of all kinds. Mind your toes if you wish to keep them."
:;The notice mentioned not to disturb the security.
:"Stinks of an inside job to me, but if our buyer wants to skim a little off the top, who are we to judge? We will charge extra for the added care, of course."''
:;I'll try not to get tripped up. Let's get on with the heist then.

When you have arrived to the cave, enter the tunnel ahead to start the timer and the objectives. You need to find seven pouches of gemstones in order to complete the quest - it doesn't matter which route you take. Be aware of various traps on the floor, especially when you are close to the enemy NPCs. There are several gemstone pouches in hidden locations, so having the floating quest objective pins is very helpful here. Some pouches might spawn in comfortable locations on your way back, so you might not need to take the whole route around the cave.

When you have managed to gather all seven gem pouches, head back to Fa'ren-dar. Beware of the elite enemy that has spawned near the exit and is rigorously patrolling the surrounding area. The timer stops once you are close to the tunnel entrance where you began the quest. Speak to Fa'ren-dar to get teleported back to Thieves Den. Back in the Den, speak with him one more time to hear whether he has managed to sell the valuables and can reward you accordingly.

Notes
Advice for faster completion and some general information:
Use potions of Invisibility with Vanish and Speed effect to sneak faster and avoid detection.
Turn on quest objective pointers to see where the quest objects are located.
If you see a collectible object very close to the entrance/in an easily accessible location, leave it until last.
As soon as you complete all objectives, an elite enemy NPC will appear patrolling near the entrance area. Thus, you will need to plan additional time when heading back to Fa'ren-dar.
Dying will not affect the timer.
Being detected by the mobs reduces the timer greatly (by one minute), risking to fail the bonus objective.
If you are running out of time or made a mistake, you may choose to Abandon the quest and re-attempt it without penalty. Abandoning the quest will instantly transport you back into the Thieves Den. This allows you to experiment and practice the same quest as many times as you wish.

Quest Stages