A BIRTHDAY WATCH IS A WATCH PRODUCED THE SAME MONTH AND YEAR AS YOUR BIRTH MONTH AND YEAR

Make: Seiko
Type: Automatic
Model: Slimdate
Year of Production: March 1964
Movement: 840
BPH: 18,000
Number of Jewels: 30
Hand and Dial: 3D Gold-Filled Baton Indices with Gold-Filled Dauphine Hands
Width: 36.8mm
Lug to Lug Height: 43.3mm
Thickness: 10.0mm
Lug Width: 18mm
Bracelet / Strap: Brand-New Uber-Quality Genuine Reptile Brown Leather Strap with Gold Buckle
Pouch / Box: Brand-New EVA Type Zipper Pouch

The Seiko 840 movement replaced the 830 (AKA 8301) movement and was later renamed the 8305. The 840/8305 debuted in February 1964 until 1972. 

For Seiko Collectors and Vintage fans, this is a pre-SUWA (logo) 30J Automatic in stunning condition. The Cool Spinner Logo below the 12H marker, 6-pointed star located below the "Diashock" wordings, it's "AD" status of solid gold markers and hands and 14K 70-micron gold-filled case makes this watch a highly sort-after timepiece.

The 70-micron 14K gold-filled case, 14K solid gold hands and indices are in excellent condition and had undergone a painstaking cleaning process and almost all imperfections have been meticulously removed. There may be a few minor scratches, and age marks do remain.

The dial has been replaced with a NOS dial. The crystal was replaced with a brand-new Japan made hi-quality crystal.

The crown is original and is located at the 4H position and is nicely tucked away to prevent damage or snags. The date quickset works as it should by uncorking the crown to the first and second level to adjust the date via clockwise or counterclockwise (very unique!) and the hands respectively.

The movement was carefully stripped, meticulously cleaned, oiled, re-assembled and calibrated on 7 October 2025. It should be able to operate unhindered until the next servicing thereby providing the owner peace of mind.

Equipped with the 840 movement, it has 30 Jewels and operate at 18,000 BPH. The time-grapher shows excellent readings of 0 seconds and amplitude of 249 with a straight centered line! Such readings are exceptional even by brand new modern automatic watch standards whereby the accepted tolerance is -20 to +40 seconds a day! This is a testament to the quality, excellent power reserve and longevity for such a vintage timepiece, the meticulous care provided over the years, and of course the painstaking expert calibration.

To the best of our knowledge and expertise when overhauling the timepiece, the watch is 100% original Seiko components from this particular watch. No parts were replaced with aftermarket parts or modified thereby it is considered in excellent condition.

Due to its age, this timepiece has not been water-resistant tested.

The case width and height are approximately 36m (without crown) and 44mm respectively. The lug width is 18mm and the genuine leather saddle strap can accommodate wrists up to 20.0cm; hence suitable for men and the modern women.

The watch comes with a brand-new uber-quality genuine reptile brown leather strap with gold buckle as part of the deal. 

The pictures provided shows the watch in stunning condition, and the movement within squeaky clean and well maintained. It has also been demagnetised to improve parts reliability, minimise wear + tear, and improve accuracy. The only drawback is the lack of documentation and original box. A nice purposeful carrying case or box will be provided instead.

Bear in mind that this watch has seen many of the previous owners’ ups and downs in life and should be cherished and well taken care of for the next generation to savour such engineering beauty.

This extremely rare timepiece will make a beautiful birthday present for that special someone born in the month of March 1964, and its value will appreciate over time.

This is a super rare Seiko Slimdate Cal 840 in stunning condition; so, be unique and own a March 1964 Birthday Watch that is almost impossible to source in such stunning condition or purchase it for that special someone instead.