Need help with collectability

[Hieral]

I'm more concerned with how appraisals don't increase rarity according to your perception, like the tool tip says. With 450 perception, the 1.1 x appraisal gives me 100 rarity, not 495.

[TechnoTechie]

I'm more concerned with how appraisals don't increase rarity according to your perception, like the tool tip says. With 450 perception, the 1.1 x appraisal gives me 100 rarity, not 495.

I'm just going to say that the tool-tip was likely mistranslated; and keep in mind the English version of the game is probably 100% translated from Japanese, with nothing from English being translated TO Japanese.
On that note, every 5 perception is worth about 2 rarity with exceptions on the higher or lower end of the spectrum, and yes it's a spectrum, because there appear to be hidden decimal values that relate to 1.0x that don't always math out to the right number when you take the integer value at 1.5x or 0.9x and apply the proper rounding (or the game is not doing proper rounding).
Another thing to note, is that every item has a separate floor or ceiling with respect to perception; meaning that your 450 perception is worth 100 rarity on that one item (I assume it's a level 54?), but it'll be worth 86 rarity (at 1.0x) on a level 56 item, and only 80 rarity (1.0x), on every item that's 58 or higher (I'm unsure if there's even a level 57 collectable?).