I can appreciate authors explaining how their skills work, but this one just keeps yapping about either obvious or ridiculously false concepts. The entirety of MC's internal monologue in this chapter looks like thoughts of an eight-year-old that is discovering the world or creating imaginary powers. It's all basic shit, but it's presented like the most profound knowledge.
For example:
Transparence doesn't relate to color. On the other hand, if something has no color, which means it has no color, even black or white.
So what happens if something has no color and is transparent? Hold on, what am I thinking now.
Transparency DOES relate to color.
Color arises from the interaction of light with a material—absorption of specific wavelengths or reflection/scattering of light.
If a material neither absorbs nor reflects light, it cannot impart any color to the light that passes through it or is incident upon it.
Theoretically, a completely transparent material, like perfectly pure glass or water (in idealized conditions), would appear colorless because it doesn’t interact with light in a way that produces visible color.
So yes,
complete transparency in the sense of invisibility implies that the material would lack any perceptible color to the human eye because it doesn’t interact with light in the visible spectrum.
And we are, in fact, talking about complete transparency here, since the hairpin MC created is invisible.