Automatic K-150
1955–1957 · 18k Solid Yellow Gold / Stainless Steel · Automatic
About the Automatic K-150
Made from 1955 through 1957, the Automatic K-150 is part of Hamilton's broader Automatic family and runs on the caliber 661, a 17-jewel self-winding movement with sweep seconds. The case is a combination of 10K yellow gold with a stainless steel back, and the dial carries applied gold numerals and applied gold markers at the 1, 2, 4, 5, 7, 8, 10, and 11 positions, with a pearlized minute track rounding out the detail. At $175 in 1955, this was a serious purchase, and Hamilton dressed it accordingly.
Finding one in good shape means paying close attention to the dial, which can show burning near the hands on examples where the hands sat too close to the surface over decades. The textured dial and embossed Hamilton logo are period details worth preserving, and the solid 18K numerals and markers are part of what makes a clean example genuinely satisfying to own.
From the Catalog
Hamilton marketed the K-150 in 1955 with emphasis on its 18K gold numerals, luminous markers, and pearled track, alongside practical credentials including anti-magnetic construction, shock resistance, and a waterproof rating. It retailed at $175, though like all vintage watches, it should not be trusted in water regardless of its original rating.
Hamilton Catalog Images
1955
1957
What to Look For
| Dial | Look carefully around the numeral positions and near the center for any burning or discoloration from hand contact. The applied gold numerals and markers should sit flush and undamaged. Check the pearlized minute track for separation or wear, and look at the embossed Hamilton logo for any polishing attempts that may have softened it. |
| Crystal | Inspect for deep scratches or crazing. On a watch of this age, the crystal has often been replaced at least once. A poorly fitted replacement can sit unevenly and affect the overall look of the dial through the lens. |
| Movement | The caliber 661 is an automatic, and dried oil on unserviced examples creates enough friction to stop it entirely. Ask about service history. If the rotor feels sluggish or the watch winds inconsistently, factor in a full service before expecting reliable timekeeping. |
| Case | This model opens through the crystal side, not through the case back. Look for scratch marks or dings around the case back from anyone who tried to pry it open incorrectly. Also check the lugs, which have a swept profile and can show wear or thinning on heavily polished examples. |
| Crown | Check that the crown screws or pulls smoothly and that the stem engages cleanly without slipping. A worn crown or damaged stem tube can affect both winding and the fit of the seal, and replacements for correct-profile crowns can take some searching. |
The Movement
The caliber 661 is a 17-jewel automatic movement made by Hamilton in the United States. It winds itself through a rotating oscillating weight as the wearer moves, and drives a sweep seconds hand rather than a small subseconds dial at 6 o'clock. It is a straightforward and durable design, though like any vintage automatic it benefits considerably from fresh lubrication to run reliably.