Under the rule of the Rex Arché, the Guild of Coin was the supreme bank of all. They minted the Citadel-wide currency in classic gold, silver and copper; they kept tabs on inflation and they hunted down forgers with fierce ruthlessness. But just as with the Inquisition, this Vermillion-based Guild has today lost most of its influence and the Sevens - which was the then-ruling currency - has been complete devalued on the market. Instead, there are new, Tower-specific currencies and their value is determined by that particular Tower’s export and import power.
When you talk about import and export in the Citadel, you’re not talking natural resources, because there are no natural resources in the Citadel that aren’t manmade and can probably be recreated by another mage. The Azure Tower might export fine textiles, but these textiles are not fine because the Azure Tower grow a particular kind of linen; it’s fine because the spellwork of it is fine. And the spellwork is fine because the Magus weaving it, is skilled.
In other words, value is first and foremost related to different kind of spells and different kinds of Arcanas. This is why a Magus choosing a Neophyte is often such a formal affair, because in that choosing is the implication that the Neophyte is worthy of knowing the Magus’ secrets and teachings; the Magus’ value. Every Magus is a master of their craft, and thus the Citadel economy relies on rare but high quality services that ensure high quality goods. Low quality goods - fabric that will merely clothe you - is easy for any mage to summon with a simple incantation.
As previously stated, Towers are not magic-specific and each Tower can perform every kind of magic. But Towers are known for particularly valuable Arcanas and Magi, which in turn give their currency a high value.
Ivory Tower[]
Marbles: 1 arch-marble = 5 crown-marbles = 10 marbles
This is the Ivory currency, and the one with the highest value, because the Ivory Tower supplies the entire Citadel with the finest, richest grain. The Silentium Medicae Hospital also commands enormous respect, especially in the aftermath of the war, where it has formally opened its doors to any Citadellian in need of help. The Ivory Tower’s reputation is surprisingly good in the Citadel at the moment, even with their enemies, since the Silentium made a point of smuggling even enemy-soldiers into their healers’ care during the War of Suites. Today, it is the Tower with the brightest future.
The marble is a delicately crafted sphere of white material; pearl for the arch-marble, seashell for the crown-marble and simple white glass for the common marble. It has a fine metal-filigree inlay and complex runes that protect it from duplication or forgery spells. It has no obvious pictographs, but if held up against a light-source the hollow sphere will cast a pattern on the floor that make up the Scales of Truth.
Obsidian Tower[]
Corazones: 1 arch-corazon = 5 crown-corazones = 10 corazones
Like with all things, the Twin Towers collaborate, and the corazones currency of the Obsidian is almost interchangeable with marbles. The corazon hinges a lot of its value on the Ivory’s borrowed legitimacy, and both marble and corazon are minted by the same magi with the same wards against forgery and duplication. With that said, the Obsidian corazon is currently experiencing a slight decrease, because of its infighting. Commonly known for their portal and space services, the Tower has had trouble getting back to a stabilized economy after the war, and the Citadel at large is distrustful of their services. The corazon is also spheric, but of course, black. It has filigree in gold, and when held up to the light it will not only show off the All Seeing Hand but also a glitter of hard-to-explain prismacolor that breaks through the stone. The arch-corazon is made out of black opal, the crown-corazon is carved from black star diopside and the common corazon from some sort of reflective, dark mirror-glass.
Vermillion Tower[]
Ingots: 1 steel ingot = 10 iron ingots = 100 copper ingots
The ingot is the coin of the Vermillion Tower. In many old texts, it is what the entire Citadel is using or at least referring to as the value-marker, but this is no longer the case. Today they are living off of days of glory past, but are still ranked higher than the Azure currency because the Mothercommander is viewed as having taken the first step towards peace. The ingot looks mostly like unmarked, smooth pieces of their assigned metal - square - but can notoriously be linked together by an adhesive magnet effect. This makes it easier to carry them around, and it’s not uncommon to have a belt or string of ingots looped around your belt or waist. They are thief-protected by a tightly guarded spell, which makes it impossible to separate the ingot-chain if you are not the owner of said ingots.