Longines Ultra-Chron Ref.7851 Cal.431 33.0mm 1969

A technically impressive vintage piece from Longines’ golden era of precision watchmaking, this Ultra-Chron Ref.7851 blends understated elegance with serious mechanical pedigree. Housed in a crisp stainless steel case and powered by the renowned Cal.431 beating at 36,000 vibrations per hour, it delivers the smooth sweep and accuracy high-beat collectors appreciate. With its clean silver dial, applied baton markers, and original signed crown, this is the kind of refined daily-wear vintage that still feels quietly special on the wrist.

In addition, this timepiece comes freshly serviced with all parts laid out by our professional watchmaker for all to see in the images above. Little to no other dealers do this and it’s a testament to full transparency here at Montre D’or. With the Cal.431 inside running excellently as shown in the timegrapher reading above, just like it was when it left the factory nearly half a century ago.

DIAL:

• Original silver sunburst dial in excellent condition

• Slim baton hands with polished steel finish and central sweep seconds hand

• Applied hour indices with matching polished steel inserts

• Original Longines logo and crisp original wording

• Domed acrylic crystal in clear condition

CASE:

• Distinctive square shaped brushed stainless steel case with sharp angular lugs

• 33.0mm Diameter (excluding crown) / 38.0mm Lug-to-lug / 10.0mm Thickness

• Professionally polished with all sharp edges intact

• Original Longines-signed crown at 3 o’clock

CASEBACK:

• Monocoque front loading case, UltraChron Emblem behind

• Professionally polished to perfect vintage condition

• Comes with plastic protective sticker as shown

MOVEMENT:

• Longines Cal.431 – Automatic high-beat movement

• 25 Jewels / 40 Hours / 36,000 BPH

• Semi-quickset date function (advance hands repeatedly past midnight and back to 2330 to change date)

• Movement freshly serviced and in excellent condition

• Last serviced: April 2026

• Accuracy: -1.0s/day

STRAP:

• Handmade leather strap, colour and design can be changed upon request depending on availability

• Aftermarket Longines stainless steel buckle

AFTERCARE PACKAGE:

• Comes with a black presentation box + silica gel

• Complimentary PolyWatch crystal polishing kit (for acrylic crystal)

• 6-month warranty (covers non-user damage only)

• Guarantee Certificate with full service details included

• Access to our exclusive post-warranty repair services

• 7-day return policy for peace of mind

SPECIFICS:

Maker: Longines

Model: Ultra-Chron

Year: 1969

Case Material: Stainless Steel

Reference: 7851

Movement Serial: 50526636

Caliber: 431

Diameter: 33.0mm

Lug to lug: 38.0mm

Lug width: 18mm

Thickness: 10.0mm

Lume: None

Strap: Black leather strap

Box and papers: Box only

Accuracy: -1.0s/day

Movement type: Automatic

Crystal: Acrylic

Crown: Original signed crown

Last service: April 2026

Free express tracked shipping with signature upon delivery. Delivery within Singapore in 1-2 working days. International shipping may take 2–12 working days depending on destination and will be shipped via FedEx/UPS/Aramex/SingPost

Do note respective custom duties might apply which includes the recent US tariffs and are the buyer’s responsibility.

Do note that for US bound shipments the PolyWatch polishing kit will not be included in order to mitigate customs delay due to new customs requirements

Countries that we do not ship to: Afghanistan, Belarus, the Central African Republic, Chad, Cuba, the Democratic Republic of the Congo, Eritrea, Iran, Iraq, Lebanon, Libya, North Korea, Oman, Pakistan, Russia, Somalia, South Sudan, Syria, Ukraine and the Crimea, Donetsk, and Luhansk regions of Ukraine.

This is a vintage timepiece and water resistance is not guaranteed. Please avoid contact with water or moisture. Store the watch with dry tissue or silica gel to preserve its condition. We are not liable for water damage post-purchase.