In "sworn to the sword" Pearl sings the line " deep down you know you weren't built for fighting." "Built" is the one word I am focusing on. Pearl is also the only crystal gem in the show that is not made inside the earth. Pearls are made inside of mollusks and are mass-produced in real life. To make a Pearl is actually quite easy, all you really do is insert sand inside the mollusk and wait. This could also explain why she can control sand and why she takes awhile reforming her self. She also said in "Ocean Gem" that she hates fighting herself, suggesting she had to fight other Pearls at one time.