Considering you can burn diamond with mundane fire, it seems like her diamond transformation somehow prevents her from burning diamond. Breaking diamond results in more diamonds, so maybe that doesn't count as destroying it. I don't see why this wouldn't be a problem with the forge though.
What makes you think that the diamond being unable to burn is due to Chachi's transformation stopping her from something that anyone that didn't merge with diamond could do when a simpler explanation is that it's a sign that diamond holds slightly different material properties in a more supernatural world that stops anyone from burning it with that level of fire.
[Insight] Diamonds are not weak to fire.
The bolded text seems important for looking into the truth of diamond in future questions and I really want to see how using the Secret Ritual of True Spirit Refinement and Blessing of Efficiency would effect a diamond given they are linked to heaven and there powers come from there structure.
[Experiment] Diamonds are known to be connected to heaven, The Secret Ritual of True Spirit Refinement channels heavenly power into an object to boost it's performance in every way. Examining how a diamond changes when it's empowered by heavenly power will not only give us a better understanding of how diamonds are linked to heaven but it will also give insight on a diamonds other functions by increasing the effects for easier observation.
Now for the insights, lets start off with some revisions or expansions of what I saw in the last threadmark to try and fix up what was mentioned as wrong or missing.
The earlier insight into light was mentioned to have a crack in it so lets try to fix that I don't think that Lazers are relevant even if they are cool and would show that they can focus light. so lets look into how else lighting can effect diamonds and it was mentioned that UV light can cause an inner glow that can either add emphasis, change the color, or make the diamond appear hazy. Fluorescence
Diamonds are a laser scientist's new best friend
[Insight] Diamonds shine with an inner light, that can glow even in darkness.
[Insight] Diamonds are not unbreakable, but they are unalterable. The core aspect of a diamond the purity of it's endless repetition cannot be changed without destroying it. A diamond will always be a diamond unless it is completely destroyed.
Diamond clears sight to see the heavens something is missing? Could it be with clarity you can remove the distortion from your sight rather then distraction. Combine with glasses experiment. In Buddhism the diamond is a symbol of pure insight and in the Diamond Sutra, Buddha teaches us to 'cut through' delusion to find the pure truth.
[Insight] The light of a diamond reflects the values of heaven, The abyssals are hurt by the reflection not because it reflects their sin but because evil cannot withstand the touch of good without trying to destroy it. Shining fate protects from humiliation because of how evil wishes to destroy what is good.
[Insight] The rigid spirit a diamond brings is because a diamond by it's nature is perfection. As such any changes are resisted as something that moves you away from perfection.
[Insight] A diamond is a multifaceted prism that reflects the truth of heaven with each facet. It's A shimmering beacon of heavens light to show the correct path and burn away the illusions the impure use to pretend they are righteous. Leaving in the end the only truth that matters the truth of beauty in purity.
[Insight] Purity is not a subjective belief but rather an objective truth and one can study what is pure and get an objective truth. This absolute and unalterable truth is the same truth that heaven draws upon to declare what is righteous.
[Insight] Beauty is a surface level truth for a diamond, for the flaws that the diamonds reject bring out their true beauty.
unsure about
Hypothesis the Lead in the soil was not purified as the lead was a separate object sharing the same space rather then a mixture. Follow up Expirement with the differences between solids liquids and gases. Solids can use alloys, liquids mixtures, I have no idea how to test gas.
Diamonds are not used in treasures because they are not receptive to the carving of Teotl waterways, which was a key step in traditional imbuement. Can we use the forge to build the waterways into the diamond without changing what the diamond is.