In Mew Mew Power, Gretchen says that she used Rainbow Stone to design her own line of jewlery but nobody wants to give it a chance due her only being an intern worker and the stone being described as "ugly". In both the original and the English dub, it was suspected that the Rainbow Stone could be the true form of Mew Aqua/Blue Aqua but after a fight between the Mew Mews and the Aliens, it turns out that the stone only has the ability to react to it but it's not a Mew Aqua itself.