In Verdistis, Sir Patrick also qualifies as wealthy (don't tell him to 'forget about it', or he will not offer you a chance to get the armour again).
The most knowledgeable NPC in the game when it comes to necklaces would be the dwarven jeweler in the dwarven halls. If you already talked to him, <span class='standouttext'>Spoiler : </span><span class='spoiler'>the real necklace does not exist.</span> (highlight the text to read)
