The Sweetheart Necklace is an accessory which grants the player the Panic! and Honey buffs when damaged, increasing movement speed by 50% for 8 / 5 seconds and health regeneration for 5 seconds, and releases a concentrated burst of bees.
The bee spawning effect of the Honey Comb, Sweetheart Necklace, Honey Balloon and Bee Cloak do not stack. Only 1-3 / 1-4 bees will appear after being damaged regardless of how many of these items are equipped.
Any source of damage will trigger the buff except for damage-over-time debuffs like standing on Hellstone.
This is the only combination using a Honey Comb that can be sold for more than the parts could be individually.
The Sweetheart Necklace's name is a pun on how, due to it being a heart necklace and honey combined, the necklace charm could literally be called a sweet heart. It is also a reference to a sweetheart neckline.