Solar Chrono Sapphire Watch EFS-S640PB-1AVUEF

The Watch

Casio has been a watchmaking icon for over a century, consistently delivering high-quality timepieces at accessible prices. The brand offers multiple collections for different lifestyles - from everyday wear to outdoor adventure. From the Casio Edifice collection, meet the bold EFS-S640PB-1AVUEF, engineered to impress on men's wrists. Its black case is built from carbon fiber-reinforced resin, shaped in a round form measuring 44.50 mm in diameter, 50.10 mm lug-to-lug, and 13.30 mm thick, weighing in at 59 g - proportions that sit perfectly on a man's wrist. The fixed bezel is crafted from stainless steel enhanced with ion plating in a sleek gray finish and features a minute scale. A sapphire crystal with anti-reflective coating protects the dial from daily scratches and impacts while maximizing readability. A crown and two pushers at 2, 3, and 4 o'clock provide easy access to all functions. The case back delivers a water resistance of 10 ATM.

The Dial

This stunning carbon fiber dial reveals a woven black background. Its perimeter features a minute track paired with luminescent hour markers. At the center, two hands indicate the hours and minutes, while the chronograph seconds hand sweeps the seconds. Both the main hands and the markers they pass over are treated with Neobrite for enhanced legibility in the dark. A date window sits at 4 o'clock, and three sub-dials are positioned at 6, 9, and 12 o'clock to display small seconds, charge level, 30-minute elapsed time, and a 24-hour indicator. Finally, Casio signs the dial with the collection name at 3 o'clock.

Functions

Solar Power

Invisible solar cells built into the watch convert light into energy to power all functions. A rechargeable battery stores enough capacity to keep the watch running in low-light conditions.

Neobrite Coating

The hands and/or markers feature a fluorescent coating that continues to glow in the dark after the watch has been exposed to a light source.

Stopwatch Function - 1/1 sec - 30 min

Timing is measured to the nearest second, up to a maximum duration of 30 minutes.

Carbon Fiber Dial

The watch's carbon fiber dial commands attention with its striking gradients of black and gray.

Battery Level Indicator

Displays the current battery level.

The Movement

This model is powered by a highly reliable Japanese solar movement with an accuracy of ±20 seconds per month and a power reserve of approximately 5 months from full charge to the moment the hands stop.

The Strap

This stunning strap is crafted from black resin, delivering a highly flexible fit with a distinctive design and outstanding comfort on men's wrists. It fastens securely with an easy-to-use pin buckle.

Water Resistance

With 100-meter water resistance - that's 10 ATM in watchmaking terms - this bold timepiece transitions seamlessly from black-tie events to the water. Feel free to wear it in the shower, the bath, or while swimming (even during intense, high-energy laps). That said, our watchmaking experts want to be clear: this model is not designed for scuba diving, freediving, or high-pressure water jets. Remember: showers, baths, and swimming only - and keep those pushers and crown dry!