Refractometers, How Do They Work? (And Should You Buy One?)

Let's talk about how refractometers work, when they're useful and when they're not.
More resources:
Intro to refractive index: polymerdatabas...
Brix Wikipedia Page: en.wikipedia.o...
Turbo Shot Paper: www.cell.com/m...
Featured products:
Brix Refractometer: smile.amazon.c...
Generic "Yellow Boi" Refractometer: www.aliexpress...
Refractometer Magic Mushroom: Custom made by Espresso Aficionados Discord member, RenegadeGuru