WARNING:Unfortunately, this only works on items that have no gem slots in it.
Was tested on a 3.32 server on Mangos and also tested it way back in a 3.13 server that was also based on Mangos.
1) Get an item that has NO socket in it. eX: Wrathful Gladiator's Armwraps of Triumph - Item - World of Warcraft
2) Get the id of an item that has 2 sockets in it. eX: Bladespire Warbands - Item - World of Warcraft
3) Socket the item either with Socket Bracer or Socket Gloves with BS, or use Eternal Belt Buckle.
4) Open up CE and search the id of your bracer and switch it with the item from WoWhead.
5) Go back to WoW and you'll be able to attach another gem to it.