From Granblue Fantasy Wiki
Low Orbs refers to Fire Orb, Water Orb, Earth Orb, Wind Orb, Light Orb, and Dark Orb. They are much more common than High Orbs.
Low orbs are primarily used to uncap characters. They are needed for the early stars on R and SR characters.
|Uncap R to 1★||1|
|Uncap R to 2★||2|
|Uncap R to 3★||3|
|Uncap story SR to 1★||1|
|Uncap SR to 1★||1|
|Upgrade Omega Weapon to 4★||100|
|Change Rusted Weapon element
|Upgrade Revenant Weapons (step 1)||100|
|Upgrade Revenant Weapons (step 2)||150|
|Upgrade Revenant Weapons (step 3)||200|
|Upgrade Revenant Weapons (step 4)||250|
|Purchase Seraphic Weapons (SR uncapped)||5|
|Uncap SR Seraphic Weapons to 1★||10|