top of page
Citizen Challenge Diver 4-600851Y





It's no wonder why the Citizen Ref. 4-600851 Y Challenge Diver is renowned for its good looks and robust design. Featuring a 40mm stainless steel case and 20mm wide lugs, this diver’s watch strikes a perfect balance between style and durability.


While Seiko experimented with a proprietary locking crown system on the 6105-8110, which ultimately proved flawed, Citizen opted for a reliable screw-down system. This method effectively keeps water out, though the crown tubes are integral to the case. A stripped tube can render the watch practically useless or, at the very least, in need of staying dry. This issue is similar to the problem faced by owners of the late '70s Seiko 6309 diver.


The Ref. 4-600851 Y is powered by the 21-jewel caliber 6000 automatic movement, which operates at 21,600 vibrations per hour (vph) and allows for hand-winding. Additionally, it features a quick set date complication, a highly appreciated function that pre-dates similar implementations by many Swiss companies.


A distinctive feature of this reference is not only its beautiful vivid green lume but also its red date wheel, adding a subtle yet striking detail. However, the deep crystal without magnification can make the date somewhat difficult to read.


The example we have for sale is in new old stock condition, complete with its original Tropic straps, a signed Citizen buckle, the original price tag, instruction manual, and protective film still on the case back. It truly doesn’t get any better than this.


The watch currently works flawlessly and will be sold as is. Please let us know if you wish to service it.


Ships from Tokyo, Japan

Citizen Challenge Diver 4-600851Y

  • Overall, this Citizen diver is simply perfect.

    The case is sharp with no visible scratches as it was evidently well kept. The crown is unsigned and screws without any issues. The bezel is immaculate and rotates smoothly.

    The matte dial, hands, indexes, and lume are original and they're in beautiful vintage condition with the green vivid lume with no deterioration or rotting observed.

    The original tropic strap is beautiful and soft and comes with the buckle signed by Citizen

    The domed crystal is in good condition with no noticeable scratches or chips.

    The case-back and engraving are sharp and retain the light green protective film.

    The watch comes with its price tag, original straps, and instructions manual.

  • BRAND:  Citizen
    MODEL: Citizen Challenge Diver 150m
    REFERENCE: 4-600851 Y
    DIAL: Original black matte dial.
    CASE MATERIAL: Stainless steel
    CASE DIMENSIONS: 39.5mm wide (excluding crown), 46mm tall, 12.5mm thick, lugs width 20mm.
    CRYSTAL: Acrylic crystal
    CASE BACK: Screw-in Stainless Steel
    MOVEMENT: Citizen Automatic Calibre 6001
    Manufacturing date: May 1976
    Service History: Unknown
    Bracelet/Strap: Original and Tropic strap with signed Citizen buckle.

bottom of page