Précieuses

The Précieuses are a trio of fish-women who serve under Gad. They were formerly members of the Simon Pirates.

Great Hidden Treasure of the Nanatsu Islands
The Précieuses first confronted the Straw Hat Pirates when they were sailing from Itsu Island to Yo Island. After an argument caused by their jealousy of Nami who had caught Gad's attention, they engaged in combat with the crew, but were defeated.

They had a second encounter with the crew inside the ruins on Hi Island, where they attempted to take revenge against the crew for their rampage in the Fortress of Zilpah. After the crew defeated them for a second time, the treasure guardian of the ruins suddenly appeared and attempted to attack the Précieuses and Nami. However, Sanji and Gad defeated the the guardian and saved them. After Gad had a short battle with the Straw Hats and left, the Précieuses followed him.

Their third and final battle with the Straw Hat Pirates occurred at sea after the crew had attacked the Fortress of Zahado and driven Simon on the run. The Précieuses mistakenly believed that Gad had been killed by the Straw Hats because he had not returned after the destruction of the fortress. They were defeated by the crew once more, after which Gad arrived and resolved the misunderstanding.

In the end, they chose to accompany Gad on his quest to create a pirate crew that does not discriminate between humans and fish-men.

Trivia

 * The name Précieuses may come from pierres précieuses, which is French for "precious stones", another term for gemstones. The names of each member of Précieuses are also French words for gemstones: Saphir is sapphire, Rubis is ruby, and Emeraude is emerald.
 * The name may also come from Précieuses, educated and literary women in French salons of the 17th century.