Stormlight

[Markus]

Does anyone know why Stormlight is stored better in cut gems?  It seems kinda random to just put in there without a clear reason.

[The One Who Connects he/him]

1 hour ago, Markus said:

Does anyone know why Stormlight is stored better in cut gems?  It seems kinda random to just put in there without a clear reason.

It's kind of like a crystalline structure thing.

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The idea here is that the physical items (like the metals or the crystals) provide a key by which magical interaction occurs.

So, in a long winded answer, a gemstone with an impure color would be considered like a bad alloy in the Mistborn magic—it either wouldn't work at all, or would work very poorly. The chemical and color signature needs to be of a specific variety to provide the proper key to accessing the power of transformation.

And the better the cut, the longer it takes for the Stormlight to escape from the gem.

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Brandon Sanderson

The cut of the gem and how flawless the gem is has more to do with how long the stormlight stays than size.

And in a way that I am gonna try to explain it: In Mistborn, the type of power you get is determined by the metal, but more specifically, the atomic(molecular?) structure. It's what lets the power through. The more perfect the cut of the gem, the less Stormlight it lets through, in a kind of... inverse relationship.

Actually, scratch that inverse line. The design of Aons also follows this whole pattern concept, just in a more visual format. There are modifiers that can make the effect of the Aon larger, letting more Investiture through. And so it stands to reason that you can modify it to make the effect smaller, which programs the pattern to let less Investiture through. Would it be too much to assume that these more perfect gemcutters are possibly a more natural variation of this phenomenon?

[Calderis he/him]

I always viewed it this way. The better the quality cut of a gem the more light it refracts and reflects and the brighter it shines when light hits it. 

When that light comes from within the gem the same occurs, making it harder to actually leave the gem. 

Edited February 26, 2017 by Calderis
Autocorrect correction

[Mr. Staccato he/him]

It may just be me - I mean, it's been more than a year since I've read up on TWoK or WoR so my memory of the text is starting to go amiss - but I don't think the nature of gems and the corresponding amount of stormlight they can store was ever addressed in the stories. I might be wrong, maybe there's a WoB out there that states why, I have no idea. Maybe it's one of those it-is-what-it-is things?

Honestly, I never thought much about this. But knowing Brandon he might just pull some bit of esoteric logic later on on why this is the case and we'll all be "OMG that makes so much sense now, how DID I NEVER SEE IT?" but so long as that hasn't happened yet I'll stick to the it-is-what-it-is logic.

[Markus]

Ok, thanks.

[skafkas]

Yeah, the investiture is in the stormlight, the gems are just a way to hold onto the stormlight. If the gem is cut, then it holds onto it more effectively, until it is accessed in some way, or leaks out over time. Better cut = less leakage.

[ccstat he/him]

In addition to the WoB shared above, there is a relevant quote from WoK:

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Sadeas fished something out of a pouch at his waist, holding it up. A large sapphire. It wasn't infused. In fact, looking closely, Dalinar could see that it was cracked--it wouldn't hold Stormlight now.

Apparently, defects in a gem are what cause stormlight to leak. Here, the cracking is responsible. For a raw gem, you could say that any rough edges are irregularities where the light can leak out. This doesn't directly answer the question; we still don't know the root cause. Does the physical disruption of the crystal allow stormlight to escape? Is it a factor of internal reflection/refraction? Or is it instead a cognitive feature of the gem being "whole" or "broken" that matters? 

Still, it does explain why they have to replace broken gems in (e.g.) soulcasters rather than just using the broken pieces anyway. They won't hold a charge, and become useless until recut with appropriate faceting. 

On 2/18/2017 at 8:40 PM, Mr. Staccato said:

I don't think the nature of gems and the corresponding amount of stormlight they can store was ever addressed in the stories.

The closest we come is at the beginning of WoR when Sigzil wants to do experiments to test Kaladin's abilities. They decide that there is too much variation in the amount of stormlight that gems hold (or at least too many unknowns for bridge four to account for in their calculations). Since they can't establish a reliable unit for measuring stormlight, they abandon most of the scientific rigor they want to include in their tests. Maybe the ardents or stormwardens know more, but so far we (the readers) are still in the dark.

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"How can I be precise? [...] I don't know how to measure Stormlight!"

"With chips," Kaladin said. "The gemstones are precisely weighed before being encased in glass."

"And can they all hold the same amount?" Sigzil asked. "We know that uncut gems hold less than cut ones. So is one that was cut better going to hold more? Plus, Stormlight fades from a sphere over time. How many days has it been since that chip was infused, and how much Light has it lost since then? Do they all lose the same amount at the same rate? We know too little. I think perhaps I am wasting your time, sir."

 

[Pagerunner he/him]

Perception is a huge thing in the cosmere, especially on Roshar. People's perceptions of the world around them drive the nature of the spren and the surges (which can be understood as natural forces personified). It might be a property of the planet of Roshar that gems hold Stormlight. But human perception drives how well they can do that. Here's the thought process that Rosharans might have: a cut gem is better than an uncut one; a perfectly cut gem is better than a poorly cut one. Obviously, then, the higher-quality one should hold more Stormlight, right? Because it's just a better gem all-around.