Glittering Pearl

Glittering Pearls are a specific currency used to unlock Awakening Soul Shards of SR+ units.
Both recurring Glittering Pearls purchase and exchange for Soul Shards are available during specific events though recurrence itself is not very predictable (approximately once every 2-3 weeks). 
=How to Obtain=
Glittering Pearls are quite a recurrent reward in various seasonal events - Halloween, Anniversary, Christmas etc.
However the most common way to obtain it is via the recurring Pearl Purchase event by spending Diamonds:
Pearls	Cost	Max Purchases
20 	1000	1
50 	2600	2
100 	6000	2
1 	80 	200
=Exchange=
The exchange rate is always 1:1 with Soul Stones.
Assuming one starts with a 1* awakening unit, here is the number of pearls required:
To 	To	To	To	To	To 	To 	To
From	 	1*	2*	3*	4* 	5* 	6*
From	1*	- 	20	70	170	320	520
From	2*	- 	- 	50	150	300	500
From	3*	- 	- 	- 	100	250	450
From	4*	- 	- 	- 	- 	150	350
From	5*	- 	- 	- 	- 	- 	200
==Awakenings==
The following awakenings' soul stones can currently be exchanged during the "Glittering Pearls Exchange" event: