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|Featured In||The Stormlight Archive, Yumi and the Nightmare Painter|
A fabrial is a Light-powered mechanical device from Roshar that uses spren to perform a particular supernatural task. Modern fabrials typically use spren captured in gemstones, while older fabrials like Soulcasters typically have the spren manifest as metal touching (replaceable) gemstones. The magical properties of modern fabrials can usually be activated by anyone who knows how to use them. A person who creates or designs fabrials is called an artifabrian. The term "fabrial" is often used colloquially to refer to the entire device. Artifabrians, however, call that a "machine", and use the word fabrial to refer specifically to a gem with a captured spren. 
During the Heraldic Epochs, the Knights Radiant knew how to create Surge fabrials, replicating all Radiant abilities except those of a Bondsmith, using the Oathgates as a guide. Their knowledge of non-Surge fabrials, which the modern fabrial science concerns itself with, was far less advanced than that of the current scholars. Some principles, however, were known even then: among others, the lifts in Urithiru were created with conjoining fabrials. With the fall of the Radiants, knowledge of most fabrials was lost, with Soulcasters as the major exception. Over time, the stories of Radiant fabrials became vastly exaggerated, with many people believing that they were far more numerous, and much more advanced, than what modern science has created.
According to Nikli, the original Aimians used devices to terraform Aimia to make it habitable, equating those devices with early fabrials. Nikli insinuates that the scouring of Aimia was caused by destruction of these fabrials during a number of wars, perhaps the Desolations, because the islands of Aimia could not sustain life without them.
While the fabrials were known for centuries, it was only recently that the pace of fabrial inventions picked up, with creations such as the heating fabrials and spanreeds being only a few decades old at most. Most research occurs in the eastern nations of Alethkar and Jah Keved, with Navani Kholin as a particularly important patron. Half-shards, an important breakthrough in fabrial research that attempts to mimic Shardplate, were only perfected in 1173, at the tail end of the Era of Solitude.
Creating modern fabrials requires trapping the proper type of spren in a gemstone cut for that purpose. To trap the spren, artifabrians lure it to a gemstone with something it loves and knows well. The gemstone must not be fully infused, but needs to have some Light inside of it. Around seventy percent of the maximum capacity works best.
Once it is lured into examining the gemstone, artifabrians drain the Light from the gemstone, using the Arnist Method, which involves placing some larger gemstones around the gemstone to drain the Light, using a larkin, or using tuning forks. If the Light is sucked out of the gem quickly enough, the spren will be sucked into the gemstone. After the spren is stuck, the spren can be manipulated to the artifabrian’s content. The types of spren that can be captured in a polestone depend on the gem's type and color, implying that there are thousands of possible combinations. These fabrial-gems are encased in a metal wire frame, which determines the effect of the fabrial, along with the type of spren. Their power can be determined by the pattern of Light that gets filtered through the gemstone, although it cannot be seen with the naked eye. Spren corrupted by Sja-anat will behave differently in a fabrial. It is possible for synthetic gemstones to be used in fabrials.
In contrast to Surgebinding or Old Magic, most fabrials can be operated by anyone, as long as they know how to do so (the only exception being the Oathgates, which require a Radiant to activate, although that might be a security measure rather than a crucial design element). Some, like heatrials, are even capable of functioning without human input. The self-contained nature of fabrials sets them apart from most manifestations of Investiture in the cosmere, wherein the magic is accessed and directed by the user (often with specific requirements or limitations).
It appears that fabrials are affected by the frame of reference of their user. For example: a spanreed being used on a ship at sea will also transfer the motion of the ship to the conjoined spanreed unless the user can conceive of both spanreeds as belonging to the same frame of reference. The exact cause of this is unknown, but suspected to be related to spren response to human perception.
Unlike modern fabrials, the ancient Surge fabrials were created by persuading Radiant spren to manifest in the Physical Realm. Their functioning is also different: for example, Soulcasters require a request for aid, which is unnecessary in modern fabrials. However, they still do involve spren being bound to gemstones in some way - two large spren can be seen guarding and controlling the Oathgates in Shadesmar. So long as the spren are not compromised, any Surge fabrial can be recreated to operate just as it used to. Any Surge can be replicated by fabrial science. However, in the present day, some fabrials that use Surges are incredibly rare, and most of them date back to the era of the Knights Radiant.
Reactions to Metal
Once trapped in a gem, spren respond to stimuli in consistent and predictable ways. The metal frame surrounding the gem creates the stimuli the spren react to - pressing metal against a flamespren in a ruby increases and decreases heat. Spren react to different metals in different ways, with their behavior generally paralleling the Allomantic powers for each individual metal. Multiple fabrial gems can be placed inside a single wireframe, which lets them work together to create more complex results. The emotion bracelet, for example, has ten gems, with patterns in which they light up corresponding to different emotions. The God Metal which Shardblades are composed of can be used in fabrials.
Bronze in contact with a gemstone will cause it to alert someone of objects, entities, or phenomena nearby by increasing its brightness. The range of this construction is determined by how much Stormlight can be infused into the gemstone.
Pewter in contact with a gemstone will cause it to express a certain attribute in force, correlated to the type of spren trapped in the gemstone. This also drains Stormlight faster than other types of fabrials, which might be similar to how Allomantic pewter 'burns' faster than most other metals. This metal is the one used to create augmenter fabrials.
Tin in contact with a gemstone will cause it to diminish nearby attributes. These are called Diminisher fabrials. Unlike other metals, this seems the opposite of its Allomantic use, to increase sensory acuteness.
Modification with aluminum
If a fabrial is used inside a room lined with aluminum, it is impossible to sense the use of the fabrial from outside of that room. If the fabrial requires outside connection (e.g. conjoiner, and specifically spanreed), the conjoined half outside of the room will not function properly because the pairing has been interrupted. If the fabrial can be used entirely within the room (e.g. a Soulcaster), it will operate as designed but be undetectable from outside.
It is possible to alter the function of a conjoiner (ruby) fabrial to transfer only certain components of motion between the conjoined halves (e.g. A spanreed that can only transfer vertical motion, but not lateral) by inserting pieces of aluminum foil into the fabrial gemstone housing. It is thought that aluminum impacts a spren's ability to sense thoughts, and therefore this may function by blocking parts of the "signal" between the two gemstones.
The ardent Rushu's experimentation with this behavior results in a mobile chair for Rysn which hovers by being vertically reverse coupled to a heavy object (an anchor which is allowed to fall a short distance) but remains laterally uncoupled allowing for free motion when pushed. Rushu notes that the chair's rotational motion remains coupled, but believes it would be possible to fix that upon further refinement.
There are no confirmed instances of other types of fabrial being modified by aluminum in the same way. Reverser fabrials are stated to operate similarly to conjoiners and therefore likely behave similarly under aluminum modification. It is unclear what effect aluminum would have on fabrials that do not rely on two paired gemstones. Attractor fabrials would have a "shadow" if partially blocked by aluminum. Though the attraction will bend round the edges, in the same way as light would bend.
Raysium conducts Investiture, allowing it to flow from one gemstone to another. It is used by the Fused to combat Knights Radiant, pulling their Stormlight away from them, and leaving them vulnerable to attack. It appears that the orientation of the metal, rather than the pressure differential, determines which way that Investiture flows through the metal, much like a magnetic polarity.
Modern artifabrians divide the fabrials they design into five groups across three categories. Ancient fabrials, including Surge fabrials, do not fit into these categories and are grouped separately.
Appropriately named, altering fabrials qualitatively alter the property or attribute they target. Well-known examples include altering the temperature of an object or an area and enhancing or dampening the sensation of pain, though artifabrians believe there is potential for even greater types of fabrials in this category.
Altering fabrials that increase or enhance an attribute are known as augmenters. They work best with forces, emotions or sensations. Half-shards and Grandbows are examples of augmenters that increase durability. There are also heating fabrials that generate heat, sometimes called warmers or heatrials. Heatrials were first developed just before Gavilar's feast, though earlier models were much less effective. Painrials that enhance the feeling of pain also fall under this category. Pewter is used for augmenters.
Diminishers act as opposites of augmenters, decreasing the magnitude of their targeted trait. In general, they operate in a similar manner to augmenters, with similar restrictions. Painrials that decrease pain are a type of diminisher. Tin is used to make diminishers.
Pairing fabrials are, as the name suggests, created in pairs that can move in parallel, or the opposite, over great distances. This category was a recent discovery during the War of Reckoning. Force is conserved between each pair of fabrials, and the force required to move one is equivalent to one required for moving both. The farther apart the two halves are, the more resistance is felt when moving them. Despite limitations in how far the fabrials can be separated and still work (dictated by certain processes during manufacture), conjectures about possible applications are being discussed.
By using Raysium, a half-spren trapped in one half of a conjoined pair of gems can be transferred to another gem, not part of the original pairing. This can lead to an asymmetry between the movements of the two spren halves, as moving a larger gem a certain distance will now make its smaller paired counterpart move a larger distance. This does not, however, allow for force multiplication.
Conjoiners are created from infused rubies which are split in half after the spren is already captured. The two halves are then able to exhibit parallel movements over large distances. Spanreeds are the most widespread example of conjoiner, linking two pens and allowing for long-distance communication. Conjoined rubies don't drain much Light to maintain their connection.
Reversers are created in a similar manner to conjoiners, using an amethyst instead of a ruby. The two halves are then able to exhibit equal, but opposite reactions; lifting one would cause the other to be lowered.
Warning fabrials detect things and give notice to the user. Their range depends on the the amount of Stormlight infused into its fabrial-gem.
Alerters use a heliodor to detect the presence of objects, feelings, sensations, or phenomena, and warn the user. There are alerters which can detect approaching people while excluding certain persons from detection. The Emotion bracelet is an alerter able to detect different emotions. Bronze is the metal used to stimulate these types of fabrials. Theoretically, a fabrial could be used to detect emotional Allomancy.
These fabrials mimic the Radiant ability of Soulcasting.  A Soulcaster fabrial consists of two rings and a bracelet connected by chains which hold a group of three gemstones across the back of the hand. Most are only able to effect small, singular changes, such as turning stone into water, while about one in ten can effect any change. They can be activated by tapping one of the three gemstones when holding the hand against what is to be changed. They manipulate the Surge of Transformation.
Ancient Radiants possessed fabrials constructed from a large topaz and heliodor that were able to "regrow" and repair injuries through manipulating the Surge of Progression. In the present day, they have been lost; however, the Herald Nale possesses one capable of bringing someone back even from the brink of death.
These fabrials manipulate the Surge of Transportation, and allow the user to transport anything on top of the platform and in the control chamber between Oathgates in an instant. However, as far as is known, they function in pairs - an Oathgate in Urithiru only connects to one Oathgate outside, and the Oathgate outside only connects to one Oathgate in Urithiru. They can only be activated by living Shardblades, as wielded by the Knights Radiant, or an Honorblade. Transportation of more than one person through them requires use of more Stormlight.
Rosharan clocks are fabrials, with their mechanisms powered in some fashion by an infused smokestone in their center, holding a captured logicspren. They are noted as being rather expensive, although in recent years they have become more and more common. Dozens of them can be found in Kharbranth. Many have bells hanging from them to announce the hour. In the past, they came only in standing and hanging varieties. Recently, Navani has managed to create a design small enough to wear on one's hand.
Used to attract certain substances, possibly determined by the gemstone used. They use iron in their metal lattices. During the Battle of Narak, Navani unveils one capable of drawing moisture from the air, pooling the water into a globe around the garnet that powers it. Shallan spots one that gathers smoke from a fire in the Ghostbloods's hideout at the Shattered Plains. The Wandersail is said to have stabilizers made from attractor fabrials that move weights inside the hull to prevent capsizing.
It is possible to create a repeller fabrial, possibly using steel.
Though their name is unknown, these fabrials can partially drain Stormlight from gems to diminish their glow, for aesthetic purposes.
The lifts in Urithiru are related to conjoined fabrials working together with sets of gears. There are empty slots on the railings on which infused gemstones can be inserted, from which the lift will draw Stormlight and begin to move. The lift draws enough power to reach the next floor, and upon reaching the first destination the platform will keep drawing Stormlight from the gemstone to perpetuate the operation of the fabrial. If at any point during the rise or descend the gemstone is removed, the lift will continue to travel until the following floor, stopping at that position. A lever on the platform can be switched to determine the direction of motion.
The wristwatch that Dalinar receives from Navani includes a stormclock, which might be a fabrial, although it might as well operate purely mechanically. The vambrace is also equipped with a clock and a diminisher painrial, while Navani's own version has a switch that allows it to turn into an augmenter, for self-defense.
There is a column of gemstones in Urithiru's lower levels which serves as the main residence for the Sibling and an access point for all of the fabrials found in Urithiru. A certain pattern of gems control the Tower's defenses against the Fused. Raboniel used it to corrupt and disable these defenses. The column also has a defense mechanism designed by Melishi in the form of a glowing barrier that can be activated by four nodes found throughout the tower.
Stormlight transfer device
Threnodite shadow detector
- It is possible to create an analog computer using fabrials.
- The term "fabrial" will, eventually, come to be used for all magic-based mechanical devices in the cosmere, such as the mechanism that picks Elantrians.
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