Apatite is a gem with multiple blue hues on their body. They were originally formed and created for the court of Blue Diamond to serve as a tactician to aid in the war for earth caused by the rebellion of a subsect of gems created by Pink Diamond on earth. They emerged too early, their colors appearing to vibrant and "raw" as a result.

Apatite is a soft spoken gem who doesn't like to anger those they see as "above them" for fear of punishment like they would receive on homeworld. Their specific gem class Blue Apatite is snugly fit just between Agates like Holy Blue Agate, and Lapis'. As they may not have the physical abilities of either but they are not a gem type to trifle with.

Apatite defected from homeworld after the war due to losing their commander and lover during a battle. The same one who later returns though heavily damaged as his gem is cracked and he suffered a partial corruption. They however never left due to also having a partner on homeworld still loyal to the diamonds. So they stayed to protect her until she later defected (this is still unconfirmed by my partner but it's heavily implied as they all end up happy on earth living in a similar manner to Lapis and Peridot but not in Beach City).