Pink Moon Crystal
Pinku Mūn Kurisutaru
Transforming into Eternal Sailor Chibi Moon
The Pink Moon Crystal is the much more powerfully evolved form of Chibiusa Tsukino's very own Sailor Crystal.
This is not a different version of the Silver Crystal itself. This was born of Chibiusa's tear when Sailor Pluto had "died." Usagi Tsukino, as Sailor Moon holds her crystal while Minako Aino, as Sailor Venus holds the future Silver Crystal in the final acts of the Black Moon arc meaning there are three separate crystals.
By the time Chibiusa becomes Eternal, she is able to harness this crystal much like her mother can harness the Silver Crystal.
The Pink Moon Crystal helps Chibiusa transform into her evolved Eternal Sailor form, which can help her perform extremely powerful moon-based attacks.