Adam Freedman’s The Party of the First Part: The Curious World of Legalese is printed in blue ink. How surprising! The book is in same color as Freedman’s blog, but you wouldn’t have realized that from either looking at Google Books’ preview or Amazon’s “Look Inside”.
I wouldn’t have noticed the blue ink either if I weren’t reading the book in its hardcover, first edition format. Although this difference in the color of the ink used isn’t “a difference which makes a difference” for me, I still feel a small chord of pleasant surprise on looking at the indigo text. Such material variability in books when you least expect it!