Mother-of-pearl-dial watches

Mother-of-pearl (MOP) dials are slices of nacre — the inner shell of certain mollusks — finished thin enough to use as a dial face. Each dial is unique because the iridescence pattern varies by shell. MOP appears most often on ladies' references (Cartier Ballon Bleu, Rolex Datejust 31 MOP variants) and on some unisex Tudor and Omega pieces. The dial reads dramatically different in different lighting — flat under tungsten, holographic under daylight — which is either the appeal or the contraindication for daily wear.