After ceramics was added a couple years ago, I noticed how limited its glazes were. There were many traditional sources of glazes that were even listed in comments in the raws as being traditional glaze materials that were not used.
As such, I made
a small mod that added 19 possible materials for glazing.
To make it so that glazing didn't take up a whole ore, I added in a millstone job to grind a boulder into a powder that could be used one-at-a-time.
Now, there are a few oddities with how it's set up currently. To keep it out of the sand bag pile, I set it as "bone powder" in the stockpiles, so it's listed under that heading in food. I also needed to expand the size of jugs to fit the powders, (whose size was not raw-editable,) although this has no apparent game effect, as all actions to put things into jugs require an empty jug, anyway.
The interface has four types of jobs for grinding, which basically allow you to say you only want to use less-valuable ores, or to specify only white ores. It also has options for glazing, including ash glazing specifically, monochromatic glazing, dichromatic glazing, and polychromatic glazing, requiring a white glaze, a "reddish" glaze, a "bluish" glaze, and a "yellowish" glaze. (Categories being somewhat vague where brown-orange glazes would be counted as "red enough", for example.)
Many of the glazes are actually adding an economic use to otherwise useless stones. (For example, cinnabar, AKA, China Red.)
Looking at the rest, I think this mod is "modest enough" for inclusion, but open for criticism on that front. Some of the things like the bone powder stockpiling can certainly be changed.
Beyond this, there is also the fact that similar processes were used for stained glass making. Traditionally, stained glass in Medieval Western Europe was made through the deliberate addition of iron, copper, and manganese ores, both of which are also glaze powders. (Technically, the state of oxidation also further changed the color, making iron be either red or blue based upon the state of oxidation, but that's getting a little tricky interface-wise to represent.)
This would allow for a wider variety of colored windows or gem windows that have that three-part flashing "animation".
Enamels are also a similar branch of non-organic dying, being basically stained glass applied onto metal or ceramic objects. Hence, you could make a red enamel decoration upon a battleaxe or throne, for example.
All of these come with the caveat that the raws as they stand do not support the addition of actual images as with engravings, only banding rings of color or similar basic concepts.
Except for creating a class of different colored glasses for windows, these are mostly going to result in additional decorations options that do not have much in-game impact, and are mostly for the interest of those who enjoy such details in the game, or their historical significance, or who just want to finally have a use for some of that orpiment you've got lying around.