Step by step guide:
1. Loot [item=139886] at /way 50.1, 75.9. Yellow blip appears on minimap when you get close.
2. Loot [item=139887] in the market stalls at /way 50.0, 77.1. Yellow blips appear on minimap when you get close.
3. To get [item=132867], kill [npc=109473] at around /way 50.8, 84.3. Harder to get to, but they seem to have much higher drop rates. Alternative (and lower) drop source is [npc=114470] at /way 48.5, 72.3 and /way 50, 76.1. Beware, both types of mob can see through stealth and masquerade.
(Don't worry about the comments saying only female Orbitists drop it. It was hotfixed and both genders drop it now.)
/tar Duskwatch Shroud
/tar Duskwatch Orbitist
/script SetRaidTargetIcon("target", 1)
4. Turn the quest in to [npc=93543] at the jeweller's in Dalaran /way 39.6, 35.0.
Notes:
*Hide in [npc=107373] like the one at /way 49.3,72.9 when things get too hot for you. You drop aggro and become invisible to them as long as you sit in it.
*Highly recommended: If you can't stealth, complete Suramar quest Masquerade to get the disguise [spell=213213] for greater ease of movement through the city. Enemies become neutral instead of hostile, except for the few that can see through your disguise.
TheWoWDB
Spell: Design: Class NecklaceTeaches you how to make a necklace specific to your class.