On the page it states that only nine of the polestones are used in spheres. I read the quote from the book that gives this information (Shallan uses a mix of spheres for light) and it says that they give off nine different colours. Since heliodors are yellow-green, wouldn't their light mingle with the light of the emerald and topaz spheres, so there would only be nine distinguishable colours even though there are ten different spheres? Or has it been confirmed that there are only nine gemstones used in spheres? Just a theory.
- I DO think the statement "Only nine of the ten Polestones are used in the spheres" is too strong. We don't know that this is the case. But I do think it is the more likely explanation. The quote, for reference, is: "she was forced to use spheres of all nine colors and all three sizes." I don't like the explanation that heliodor light blends with two other colors. All light blends together, and there are others that match more closely in color. Perhaps it's two other gems that are considered the same color (e.g. ruby and garnet)... Yet they must be considered separate colors, since color is the primary way to tell them apart. And Shallan seems to be referring to gem color- not resulting light color. Furthermore, Brandon has emphasized that the color of gems really matters on Roshar. For the purpose of soulcasting, for example, the color is the main thing that determines what stone you're using. This also strongly suggests each gemstone is a unique color. Therefore, the best explanation is that only 9/10 gems are used in spheres. -- Jofwu
Smokestone *is* used as evidenced by the fact it's part of the library.