A Pearl Tear is the ultimate source of a Mermaid Princess' power. The Pearl Tears of the seven Princesses are
what Gaito and his minions are after, because they possess the power to sumon Aqua Regina. They're the pearls that the Mermaid Princesses keep in their Shell Lockets. Truthfully, the lockets hold no power whatsoever and it is actually the pearls that are powerful.
- A Pearl Tear allows the Mermaid Princess of its possession to transform into her Idol Form.
- A Mermaid Princess cannot sing well without a Pearl Tear.
- It enables a Mermaid Princess to have her Coming of Age Ceremony, as it is connected to Aqua Regina.
- A Pearl Tear has the power to heal someone, as Lucia's did when Kaito nearly drowned.
- A Pearl Tear's shine can blind or harm a villain, just like how Karen's did in episode 27 of the first season, so that Lucia, Hanon, and Rina could escape the Black Beauty Sisters. Another example is Hanon when Yuuri tore Mitsuki's sheet music.
- Coco and Noel's pearls have been used by Sheshe and Mimi for them to sing more powerfully. In the second season, they were granted power which let them sing just as powerfully without a pearl to empower them.