@randomfish

Thank you, and here https://www.metafilter.com/183742...

100 grams = 1400 USD!

Imagine the smell

Fun novel about blue paint: Sacré Bleu by Christopher Moore https://www.chrismoore.com/books... It’s a funny story, very enjoyable, very imaginative.

IIRC the expense is why blue is so rare in European painting before the 18th century, when Prussian Blue was first synthesized. You can make it pretty easily at home with a handful of ingredients or just buy laundry bluing.