Pure Hearts are known to be unbelievably powerful, which helped Mario and his partners to overcome situation that seemed dire, such as removing an enemy's invincibility and strengthening the heroes' power.
The main purpose of the Pure Hearts is to banish the Chaos Heart by combining into the Purity Heart with the massive power of love between someone, such as Count Bleck and Tippi's eternal vow proved powerful enough to combined the summoned Pure Hearts into the Purity Heart.
However, while they are powerful, they are not indestructible, as seen when the void drained away the power of the Pure Heart along with the entire Sammer’s Kingdom, turning it into an ordinary heart shaped stone. Queen Jaydes has shown to be able to revitalize this Pure Heart using her powers over life and death, and is probably the only one who can do so.
Below are the location and keepers of each Pure Heart,
- Red: Kept by Merlon. It was given to Mario at the start of the game. (Refusing to take it will result in a game over, before the player even gets to control Mario)
- Orange: Kept by Merlumina. It was given to Mario and his partners after he defeated the guardian Fracktail, who agrees to let Mario pass before he became malfunctioned due to being electrocuted by Dimentio and attacks him.
- Yellow: Kept by Merlee and her ancestors. It was given to Mario and his partners after he defeated Mimi, who has been threatening Merlee for the Heart.
- Green: Sealed in Fort Francis. Tippi's newfound trust of her new friends summoned the sealed Pure Heart after Mario and his partners travelled all the way to Fort Francis and defeating the evil tech geek Francis just to save her.
- Blue: Kept by Squirpina XIV and her descendant, Squirps. It was given to Mario and his partners after they arrived at the secret chamber of the Whoa Zone and defeated Mr. L and his Brobot.
- Indigo: Kept by the King Croacus generations. It was given to Mario and his partners by the Floro Sapiens after they defeat King Croacus IV, as a thanks to their assistance in making a peace treaty for the Cragnons and the Floro Sapiens.
- Violet: Kept by King Sammer. After Sammer’s Kingdom is destroyed, the Pure Heart Mario and his partners found in the remains of the world lost its power and became nothing more than an ordinary heart shaped stone. After Mario is sent to The Underwhere by Dimentio, Queen Jaydes revitalized the Pure Heart with her powers over life and death in return of Mario agreeing to help her locate Luvbi.
- White: Kept by Queen Jaydes and King Grambi, who transformed the Purt Heart into Luvbi. After a heated argument between Luvbi, who discovered the truth of her identity from the speeches of Bonechill, and her "parents", who aren't exactly her parents but still loved her like she is their child, Luvbi assumed her true form and the Pure Heart is given to Mario by the king of The Overthere, but at the promise of Mario must not fail to save all the world from Count Bleck's clutches.
The Pure Hearts are summoned and used in:
- The unity of the 4 heroes in the Light Prognosticus, Mario, Princess Peach, Bowser and Luigi, summoned the first set of Pure Hearts and disabled Count Bleck's shield.
- The loyalty of Count Bleck's minions, O'Chunks, Mimi and Nastasia, even after their boss became an ally to Mario having been freed from the clutches of the Chaos Heart, summoned the second set of Pure Hearts, which lowered Super Dimentio's defense, and fully restoring Mario and his partners' health, allowing them to battle and defeat Super Dimentio.
- The eternal vow of the long lost lovers, Count Bleck (Blumiere) and Tippi (Timpani), summoned the final set of Pure Hearts. The power of the lovers' vow is so strong the hearts combine into the Purity Heart and banished the Chaos Heart once and for all, and also restored everything back to normal.
The Pure Hearts are also required to be set in the Heart Pillars located all around Flipside and Flopside, each Heart Pillar set with a Pure Heart will open up a dimension door leading to the next Pure Heart, with the exception of the 8th and final Pure Heart, which opens up the dimension door to Castle Bleck on Flopside Tower.
For the locations of each Heart Pillar, see Heart Pillar.