Automatic K-375
1955–1958 · 10k Yellow Gold Filled / Stainless Steel · Automatic
About the Automatic K-375
Made from 1955 through 1958, the Automatic K-375 is part of Hamilton's broader Automatic family of self-winding dress watches from that era. It runs on the caliber 661, a 17-jewel automatic movement, and comes in a 10K yellow Gold Filled case with a stainless steel back. The dial is silver with applied gold numerals at 3, 6, 9, and 12, applied gold markers, and a luminous pearled track, with solid 18K gold used for the numerals themselves. A sweep seconds hand completes the layout.
The detail worth watching on any K-375 is the dial. Hamilton specified solid 18K gold numerals for this model, which is a meaningful distinction from the gold-tone printing found on lower-tier references. Luminous material on the markers can yellow or flake over decades, so examine those closely. The silver dial finish is relatively forgiving of age, but any burning or discoloration around the center, which can happen when hands sit too close to the dial surface, is something to scrutinize before buying.
From the Catalog
Hamilton listed the K-375 in 1955 at $100.00 on strap, marketing it as a 10K yellow gold overlay watch with a stainless steel back, sweep seconds, and 18K gold numerals on a luminous dial with a pearled track. The listing also noted anti-magnetic, shock resistant, and waterproof ratings, which were meaningful selling points at that price point in the mid-1950s.
Hamilton Catalog Images
1955
1957
1958
What to Look For
| Dial | Look closely at the applied gold numerals and markers. The solid 18K gold numerals should have a warmth and weight to them distinct from plated or printed versions. Check for burning or discoloration near the center of the dial, which can result from hands making contact with the surface. Luminous material on the markers often yellows or flakes on unworn examples, so assess the condition of those carefully. |
| Crystal | On this case design, the movement is accessed through the crystal side rather than the case back. This means some sellers may have tried to pry open the case back mistakenly, leaving tool marks around the case back edge. Inspect the crystal itself for chips, crazing, or deep scratches, and check the case back for evidence of forced-entry attempts. |
| Movement | Ask about service history. The caliber 661 is an automatic, and dried oil creates enough friction on unserviced examples to stop the rotor and mainspring from doing their job properly. A watch that winds manually but stops on the wrist is a common sign of a movement that needs cleaning and fresh lubrication. |
| Case | The 10K yellow gold-filled case will show wear through to the base metal at high-contact points over time. Check the lugs and case sides for polishing or wear-through. A case that has been aggressively polished loses its original lines and drops in collector value. |
| Crown | Check that the crown threads smoothly and seats properly. A loose or damaged crown can compromise the seal and is worth noting, especially since the original waterproof rating no longer applies to any vintage watch regardless of how it was marketed. |
The Movement
The caliber 661 is a 17-jewel automatic movement made by Hamilton in the United States. It winds itself through a bidirectional oscillating weight as the watch moves on the wrist, and it drives the sweep seconds hand directly from the center. It is a solid, reliable movement for its era, though like any automatic that has gone years without service, dried lubricants are its most common enemy.