Mad necklace

The Mad necklace was obtained from Diango for players who were members throughout the month of May in 2012. After talking to Diango, players must ask "Do you have anything else?" to redeem the necklace. On 1 June 2012 all players who had been a member for the entirety of May got a message after logging in stating ''You have obtained the Mad Necklace! See Diango to claim it.''

After equipping a message states "You feel empowered by the festivities of May." and after unequipping a message appears stating "You are no longer empowered by the festivities of May." When worn it gives 250k bonus experience in any skill and works the same way as the Sköll boots and Hati paws with checking the charge.

The experience multiplier does stack with Constructor's outfit, Golden mining suit, Lumberjack clothes and with Citadel Bonus XP. It also stacks with player owned house altars. The necklace gives the full 2x boost to Summoning whereas on the Bonus XP Weekends, Summoning was only given a 1.1x boost.

It may be ill-advised to train combat skills or Slayer with this because it would give double exp in both the stat you are training and Constitution. This would use the charges up at a faster rate than if used on a single skill. As for Slayer, the charges would be used on the combat skill you are using, Constitution, and Slayer as well.

The necklace does work for bonus Dungeoneering. It can be taken into the dungeon and equipped at the end to provide 2x Dungeoneering experience (tokens will not be doubled). Note: equip the necklace only when moving to the next dungeon if you want all the experience solely for Dungeoneering.

The necklace also works inside the Runespan, even doubling the experience received from locating the yellow wizard. Like Dungeoneering, points earned will not be doubled.

Notably, this necklace's effect stacks with the effect of the Goldsmith Gauntlets giving a little over 112 exp per gold bar, granting the player with incredibly efficient Smithing experience.

The necklace also works inside the Clan Citadel, doubling the experience from all plots.

When all the charges are used, the item is reduced to a cosmetic item, similar to the Hati paws and Sköll boots. You will not get a message when this happens.

On 1 September 2012, a day after the release of the 350k exp promissory notes, all the Mad Necklaces were reset to zero charges without any warning or hint from Jagex. On 2 September 2012, the charges were then re-enabled due to complaints by players.

Since the Bonus experience update, the mad necklace, if not already depleted, now has a "Give xp" option.

Experience not doubled

 * Bonus experience gained from a special slayer task
 * Dungeoneering experience bought with tokens
 * The Refer a Friend Programme experience boost will not stack
 * The effects DO NOT stack with the passive 10% exp boost achieved by purchasing membership at the RuneScape stand at the recent MCM Expo event
 * Sacred clay items
 * The Ectofuntus
 * Experience lamps
 * Experience bought in Soul Wars
 * Agility Arena tickets
 * Teleporting a full urn of any kind
 * When used in conjunction with a Penance horn, the experience gained will only be doubled, and only use the horn's charges. The experience gained pop-up atop the screen will show the experience as if unaffected by either boosting item.
 * Runite Smelting at the Blast Furnace (1.5 extra xp received regardless of how many are smelted)
 * Experience gained from making unfinished potions with the Factory set is not doubled
 * Giving sq'irk juice to Osman in the Sorceress's Garden.
 * Defeating the wild jade vine, but it does work on checking health for farming experience
 * Cutting Lapis lazuli gems
 * Experience from distractions and diversions
 * Skeletal Horror
 * The Pit
 * Penguin points
 * Tears of Guthix
 * The Circus
 * Adding a pair of rocks to the statue in the Shattered Heart

Trivia

 * Unlike other bonus experience items, some static experience amounts such as the slayer reward from Bork are affected.
 * This is the first neck-slot item to have a graphical effect when equipped and unequipped. The graphical effect of the Mad Necklace disappears when it's all used up.
 * The description of the Mad Necklace references real rumours concerning the necklace. Many players misunderstood the description of the bonus that would be given at the end of Mad May, thinking that it would be an experience lamp worth 250,000 experience.
 * If the necklace is used at the point before running out of charge (even 1%) on a dungeon, it will still double ALL of the dungeon's experience, making dungeoneering a great choice for the last few charges of the necklace.
 * If the last charge of the necklace is used while making Summoning pouches, it will double the experience of all pouches made simultaneously. This can give as much as 24365 extra bonus xp when used while making Talon beast pouches.
 * If the necklace has less than 1% of the charges remaining when you Check charges, the message reads "Your necklace has almost run out of power."
 * The examine info of the Mad Necklace is a reference to Mark Twain's quote, "The rumours of my death have been greatly exaggerated."
 * If a player does not accept their Mad necklace within 15 days, they will get a message on screen saying "Want your Mad May necklace? Talk to Diango in Draynor Village marketplace and ask 'Do you have anything else?'"
 * Although most amulets can be seen, this one cannot when wearing certain body armour, like an Armadyl chestplate.
 * The graphical effect when wielding the necklace is similar to that of the prayer renewal potion and the Pendant of Skill.
 * When using the "Give xp" option, the interface would show 0 xp for any skill, although it will still properly grant the bonus experience upon confirmation.