Apparently this can be used to add a gem slot to artifacts that don't have one.
Useless mod. Don't waste tokens or gold.
Does not give additional socket (i.e if using it with an item and max azoth, or if using it in jewellery where perk slot is already filled by craft).
As of 2021-10-31 it does not work; the perk-item gets consumed, resulting in a blue craft without the gem socket.
The Gem Setting Pins can be bought from your faction Adjudicator, located in every city/outpost.
You need to have reached the 4th Rank in your faction.
Those are the only way to put a socket on some of the new Season 3 artifact weapons.