9RA5 Professional Diver's 600M

Grand Seiko 9RA5 Spring Drive 5 days

In 1999, Spring Drive was born. It combines the best of mechanical and electronic watch technologies in a watch powered by a mainspring that offers accuracy of one second a day. The seconds hand moves in perfect glide motion and, through it, expresses the natural and continuous flow of time that resonates so deeply with the Japanese sensibility. This year, Grand Seiko introduces a new generation Spring Drive caliber, 9RA5, that is slimmer, even more precise and has a greater power reserve.

In comparison to the 9R6 caliber that is the mainstay of the current collection, Caliber 9RA5 delivers a five-day power reserve, an increase of 60%. Its monthly precision rate has risen from ±15 to ±10 seconds a month. The movement depth has been reduced from 5.8mm to 5.0mm and the speed of the date change has been greatly increased. All these improvements are made possible by new key components including a re-designed and re-positioned Magic Lever and a new IC package.

To demonstrate its power, strength and precision, the first creation to be powered by Caliber 9RA5 is a professional diver’s watch. It has helium and water resistance that meet the challenge of saturation diving at depths of up to 600 meters. The case is in high-intensity titanium, which is 40% lighter than steel and more impervious to scratches.

The dial color is the Grand Seiko blue and the edges of the case have the sharpness that only Zaratsu polishing can achieve. The intricacy of the case with both hairline and mirror finishes in titanium needs extraordinary skills and years of experience to accomplish and the polishing takes many more hours than a case in stainless steel. The watch’s valve-free helium resistance is made possible by the special case construction and the L-shaped gasket. The grooves on the rotating bezel are deep for secure use even with gloves. The bracelet has a sliding extension setting to accommodate pressure changes.

Even though the solid case back prevents it being visible, in its finishing, also, the movement has a beauty that is uniquely Japanese and is inspired by the natural environment near the studio where it is made. The jewels echo the glittering stars that sparkle especially brightly during the early days of winter in the surrounding mountains and the delicate texture of the movement’s surfaces reflects the frost that winter brings to the trees.