My understanding is that you could get them from your reward mail for being on the leaderboard for weekly vMA, but then they changed it so that it's 100% chance to get a Maelstrom weapon as the reward, effectively removing the jewellery from the loot tables. Since that change, there is no way to acquire V16 gold jewellery. Please correct me if I'm wrong, as I'd love to know another way to score one.