In "Answers or Not," Selena finds the diary, awakening Faith from her grave. Since her resurrection as a ghost, Faith created a new one; this made Selena think that there was another mermaid like her.
The first diary was spring green in color, with pages full of Faith's life as a mermaid. It had several stripes of hot pink, purple, and lime green. The ring spine was silver.
The second diary is reddish/orange-brown, with a strange pattern on the front. The edges of the pages have details on them, as well.
The second diary has spells and information that Faith had written about magic; the girls often use it for information about mermaids and magic. It also seems to have sensory abilities, as it knew that Nikki was a mermaid.