This is SOLELY for the duplication glitch, as long as it is not patched!To start out, make your way to Solstheim via fast travel or talking to the ship captain at Windhelm docks. He will ask for 500 gold unless you progressed in the story enough to get the random encounter for a quest that leads you here. Remember, if you don't want to walk to Windhelm, make your way to the carriage at whiterun stables and he'll take you for 50 gold.
Step 1. obtain an East Empire Pendant. Easiest place I found one was in Raven Rock Mine, there's a small jewel box just a little ways in.
Step 2. Do the duplicate glitch via mercenary (or however you can else you want to do it if possible) and get around 200 or so but keep one saved somewhere. NOTE: only dupe UP TO 100 at a time or there's a great chance your game will have tremendous lag or just freeze.
Last step. Talk to the general trader Fethis Alor in Raven Rock and ask about the pendants. He will buy these off of you for 500 gold each (or depending on barter perks maybe?) And the best part is, doing it this way doesn't make you wait 48 hours for him to have money again! That's right, he has unlimited money when he buys these pendants off you!
For this reason, I believe this is faster than duping other items, because it is not as time consuming while you wait for stores to restock gold, and these pendants are light so you can carry a lot.
If there are other npc's that want a specified item, you can try this with them too. I just found this one the easiest for me.
I have uploaded a video I did to show what I mean, or for those that prefer videos.
Hope this helps!