Crystal necklace

The crystal necklace is an object owned and used by Sheeta in Laputa: Castle in the Sky''. ''Sheeta's grandmother gave her the necklace and taught her the spells she needed to say in order to use its powers. The pendant of the necklace is a blue crystal made of Aetherium ("Volucite" in the original Japanese and Streamline English versions), a rare element that glows when activated and which possesses certain magical powers. Sheeta's crystal is etched with the symbol of the royal family of Laputa.

Role in the Film
When Sheeta falls from the airship at the beginning of the film, her crystal activates and causes her to float down to the Earth without being harmed. She and Pazu later use the crystal to fall safely from the railway and float down into the mine below.

The crystal can also perform other magical tasks. When Sheeta activates it with a protection spell her grandmother taught her, the crystal awakens a Laputan robot and points the way to Laputa, which is hidden in the clouds above. When Muska tries to touch the crystal while it is active, it shocks him.

In the mine, Uncle Pom shows Sheeta and Pazu how the rocks hold traces of the Aetherium/Volucite element, and Sheeta discovers that her crystal is made of the same material. When Sheeta and Muska reach the core of Laputa, they discover a giant Aetherium/Volucite crystal there which keeps the island floating. Sheeta and Pazu speak a spell of destruction while holding her smaller crystal to prevent Laputa from falling into Muska's hands; both crystals work together to destroy most of the man-made structures on the island. Presumably, the crystal necklace is either destroyed or remains behind when Sheeta and Pazu leave Laputa at the end of the film.

Spells
There are two spells spoken in the film, though Sheeta reveals in her conversation with Pazu that there are at least two others - one for finding things, and one to cure sickness.
 * The Activation/Protection Spell: "Leetay Latuparita Ulus Aria Los Balu Netoreel"
 * Sheeta's grandmother explains that this spell is to help Sheeta when she's in trouble, and translates to "save me and revive the eternal light".
 * The Destruction Spell: "Balus"
 * It is revealed through the aforementioned conversation with Pazu that Sheeta was taught this spell with the instruction to never use it, but that she needed to know evil spells in order to give power to good ones.

Gallery
Holozit 飛行石