Actually, I think Pink left her when she was around 2,000 years old. Since Volleyball says she’s been controlled by white diamond for 8,000 years, that time gap is when Spinel and Pearl were given to her. Pearl says that she was given to Pink “a couple thousand years before she was given the Earth,” so that means Spinel was around 2,000 years old when she was abandoned, and 8,000 years old in the movie.