roshar gemstones

[jasnah kholin]

prove me wrong

On page 120 of words of radiance shallan takes in so much stormlight that the gemstones break, my theory as to why this happened is that she pulled so much that it created a vacuum of investiture and when investiture came crashing back in the gemstones broke. I think this could be of interest to the cosmere as a whole if investiture vacuums can be made. 

[Quantus]

I dont think so, but it would take in-world experimentation to prove.  Gems always and eventually crack from use, which can be from one big use or from enough repeated uses over time; this is fundamental to the gem economy.  Separately we know that imperfections in the gems cause them to vibrate when infused (which is how the Gem Archive works).  Combine those two and I think the gems shatter from entirely normal crack propagation within the crystal, which grow microscopically with each stress cycle until they catastrophically fail.  This is the same material mechanism as when you bend a paperclip back and forth until it breaks.  

The reason I think it's accumulated stress cracks and not a Burst Pressure type failure sort of thing is that they will fail over time and repeated use, not purely from exceeding the upper limit of the Gem.

[Duxredux]

A phenomenon similar to a Investiture pressure differentials definitely exists, it is important, and in fact it's foundational for how fabrials are made. From Rhythm of War Epigraphs:

Quote

"To draw Stormlight out of a gemstone, I use the Arnist Method. Several large empty gemstones are brought close to the infused one while the spren is inspecting it. Stormlight is slowly absorbed from a small gemstone by a very large gemstone of the same type—and several together can draw the Light out quickly. The method’s limitation is, of course, the fact that you need not merely acquire one gemstone for your fabrial, but several larger ones to withdraw the Stormlight.

Other methods must exist, as proven by the extremely large gemstone fabrials created by the Vriztl Guild out of Thaylenah. If Her Majesty would please repeat my request to the guild, this secret is of vital importance to the war effort."

"If the Stormlight in a gemstone is withdrawn quickly enough, a nearby spren can be sucked into the gemstone. This is caused by a similar effect to a pressure differential, created by the sudden withdrawal of Stormlight, though the science of the two phenomena are not identical.

You will be left with a captured spren, to be manipulated as you see fit."

It does seem as if higher stress applications are more likely to break gemstones, for example Jasnah predicting that a focal gem would break when she was preparing to free Taravangian's granddaughter at the very start of Way of Kings by Soulcasting the fallen stone. However, most often gemstones seem to break when the Stormlight empties from them, not when they get infused by the Highstorm. If gemstone failure was caused by a burst pressure exceeding their maximum capacity, I would expect them to break when they were infused, not when they were drained. I'd guess it's those small cracks that @Quantus mentioned that vibrate and widen as Stormlight infuses and leaves the Gem, perhaps creating stronger vibrations from the kinetic Investiture? I think both concepts may be at play.

 

Edit, here's a WoB.

Quote

Hut on a Hill

One last question, why do gems crack when Stormlight is drawn out of them quickly?

Brandon Sanderson

When the Stormlight is coming out--you'll notice that there's the slightest physical presence of lots of spren, seons. A lot of this Investiture does have a physical side to it you can feel and that much Stormlight coming through... like when it's leaking out, it is generally going through micro cracks in the structure--where the crystal lattice didn't line up or flaws in the structure--and it coming out quickly like that, it's like hitting it with a hammer from inside along those fault lines. Much less likely to happen based on how good your gemstone is.

YouTube Live Fan Mail Opening 1 (Oct. 30, 2021)

 

Edited July 12, 2022 by Duxredux
added another thought