A California Dial is a distinctive style of watch face characterized by a combination of Roman and Arabic numerals. Typically, Roman numerals are positioned on the upper half of the dial, from 10 o'clock to 2 o'clock, while Arabic numerals occupy the lower half, from 4 o'clock to 8 o'clock. The 3, 6, and 9 o'clock positions are often marked with dashes, and an inverted triangle is used at the 12 o'clock position. This design was initially developed in the 1930s and gained prominence during World War II for its enhanced legibility in low-light conditions, earning it the nickname "high visibility" or "error proof" dial. The term "California Dial" emerged in the 1980s when a California-based company began refurbishing Rolex watches with this dial style due to high demand. Today, the California Dial is featured in various modern watches, including models from brands like Panerai and Nomos Glashütte, as well as in the Apple Watch. Its unique blend of numeral styles and historical significance make it a sought-after design in the world of horology.