Mother of pearl—properly known as nacre, for those with more scientific leanings, and often abbreviated as MOP for those without them—is a material produced by some mollusks as an inner shell layer, and a prized material for the buttons on high-end dress shirts because of its strength and lustrous appearance. Oh, and it’s also what makes up pearls (c’mon, guys… it’s in the name).
A detailed take on the structure and composition of MOP will have you reaching for that textbook you never returned after high school biology, so in the interest of clarity, we’ll keep it brief. It’s comprised of layers of aragonite platelets, separated by layers of elastic biopolymers. The combination of hardness (the aragonite) and pliability (the biopolymers) at the molecular level makes for a substance that’s very strong and resilient. It’s tough enough to protect a skeleton-free sea creature—or break a needle on a sewing machine. One guess which one of those traits appeals to tailors, shirt makers and shirt owners at large.
But beyond its needle-destroying tenacity, MOP is perhaps most remarkable for being iridescent. The aragonite platelets disrupt and refract natural light, resulting in different colors being reflected at different viewing angles. Aside from the scientific implications, it looks nice. It also looks expensive—in fairness, it usually is—which makes it a great choice for top shelf shirting. Be warned, though: MOP buttons aren’t the best choice for an everyday shirt, as the material will eventually degrade over the course of repeated washings. Along with the shameless absence of “clean breeze” flavored oysters, it’s one of the chief drawbacks of mollusks not evolving in detergent-enriched water.