Here is the full list of all 20 White Pearl achievements.
Chapter 15 completed.
Chapter 14 completed.
Chapter 13 completed.
Made a decision which would change the fate of the world.
Completed the alternate ending.
Chapter 12 completed.
Chapter 11 completed.
Attended the Harvest festival at Prevesta and be granted access into the item shop.
Chapter 10 completed.
Completed the Sigil Questline, thereby unlocking access to Ancarna Castle.
Chapter 9 completed.
Chapter 8 completed.
Chapter 7 completed.
Chapter 6 completed.
Chapter 5 completed.
Chapter 4 completed.
Chapter 3 completed.
Chapter 2 completed.
Chapter 1 completed.