Corusca gems were extremely rare and valuable crystals. They were produced by a combination of the extreme pressures present in the atmosphere of Yavin—pressures great enough to crush elements together—and the scraping of the liquified air of the planet against its metallic core. The sizes of Corusca gems increased with proximity to the core of Yavin. They could be found in no other place in the Galaxy. Corusca gems were mostly valued for their beauty. The way that light reflected inside a Corusca gem would make it seem as if it had a furnace within it.