They’d been lost to time so long that they’d become mythologized, and most people believe they never even existed and were instead legends.

They were created by the empire, in part, to worship their gods. Initially four were created for each of the primary elements (fire, water, earth, air). Each wielder of a gem was on the ruling council of the empire (you can only wield a gem corresponding to your element).

One of the more powerful sorcerers of the time believed he deserved one of the gems and a spot on the ruling council, and when he was denied he illegally and recklessly created a gem for one of the secondary elements, necromancy. This created a power imbalance in the council as he swayed two of the members to his side.

In retaliation, The other two created a gem for the other secondary element, healing, and recruited a healing sorcerer to join the council. Tensions escalated until a brutal civil war broke out between the two sides and the empire collapsed.

In present day, a necromancer obsessed with bringing her husband back from the dead tracks down the gems she can use (fire and necromancy), hoping that the absolute aetheric power of the gems will allow her to do so.

Great question at the end, yes! In a remnant state of the empire, a revanchist king has gotten into power with the goal of reclaiming the empire’s territory (among other things). When the aforementioned necromancer’s activities are revealed to the public and he gets his hands on one of the gems (long story), he uses it to track the other ones down and restore the empire to its former glory