The base Production Cost for each of these constructions is 100 Industry and 8 Pearls, but the Industry cost increases by 500 (350 with ELCP) upon researching Unskilled Labor from Era III, and 1000 (750 with ELCP) upon researching Organized Labor from Era IV. Therefore, researching both increases the Industry cost to 1600 (1200 with ELCP).
The magical properties of Pearls can be used to preserve and empower all manner of basic resources.
While this blessing is one of the quickest ways to gain stockpiles for many factions, it is generally not advised to unlock this blessing, let alone use it. The relative scarcity of Pearls, combined with the fact that there are a number of constructions that can only be built with Pearls while there are a multitude of other ways to get stockpiles, means that these constructions are only useful if the player has a large stockpile of pearls that they cannot put to another use. However, the only factions that are likely to encounter this problem are the Allayi (who collect more pearls than any other faction, though they could probably be put to better use by producing more Garths or Skyfins) or the Cultists (who have little use for pearls after constructing all the unique improvements it offers in their one city).