The Order of the Candle are a coven of necromancers who live on the northern side of Windfall Island from the Oblivion plugin Windfall. The necromancers are actually quite a friendly bunch, unlike any you may have come across in the game previously.
The Order of the Candle Quests
This quest series can only be started after reaching the point where Knawl says speak to him if you want some more work in the quest An Ally in the Main Quest series.
Speak to Knawl about working for the Coven, and he tells you to go and speak to Arkyon. Arkyon has a room on the top floor of the Manor, and may be found there, as well as in other parts of the Manor.
Diamond's are a Girl's Best Friend
"I have agreed to do a special job for Arkyon, one of the necromancers that lives at the Order of the Candle. Creepy place, but profitable. Arkyon gave 100 septims in advance to search a crypt for a diamond. He also promised me another 300 if I return with the diamond. Once I am supplied, I'll head out to the Altarius Family Crypt and have a look around."
Return to Arkyon; he takes the Netherworld Diamond and gives you 300 Gold.
"Arkyon has hired me to bring the diamond to Melvin Branch in Windfall so it can be made into a ring. In addition to the diamond, I need to bring Melvin a gold nugget to make the setting. Arkyon did give me 50 septims to buy a nugget, but if acquired a nugget in some other manor Arkyon doesn't want to know about it. I like the way this mer thinks. Well, at least I know why he wanted the diamond. Now I wonder what the ring is for?"
When you speak to Melvin he takes the Netherworld Diamond, 50 Gold and the Gold Nugget from you. He recognises the diamond, and is reluctant to make the ring because of the curse. He says he is willing to still make the ring if you can get him a seat on the island's Chamber of Commerce, something he has been trying to do for some time. You need to speak to Dolores Plentius in the Town Officials in the castle.
If you don't want to pay the bribe, there doesn't seem to be any way of getting the diamond back from Melvin to make the other arrangements suggested.
If you've completed the main quest and have been made Count you can threaten Dolores into giving Melvin a seat by choosing the option "Enough of this" in conversation. Otherwise, you'll need to pay a bribe. Once Dolores has agreed to give Melvin a seat, return to him.
Melvin says he will now make the ring, and it will be ready tomorrow. He also gives you back the 50 Gold you paid him for making the ring as a thank you.
After the ring has been made, take it back to Arkyon. Arkyon gives you 300 Gold and lets you keep the horse you were loaned.
He says that Todward wants to talk to you about doing an errand, which is to search for information on a lost relic in Paranoia May Destroy You.