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