Automatic K-456
1956–1958 · 10k Yellow Gold Filled / Stainless Steel · Automatic
About the Automatic K-456
Made from 1956 through 1958, the Automatic K-456 is part of Hamilton's Automatic family and runs on the caliber 661, a 17-jewel self-winding movement. The case is 10K yellow Gold Filled with a stainless steel back, and the dial carries applied gold numerals at 3, 6, 9, and 12 with gold dot indices filling the remaining hours. Hamilton marketed it with a sweep seconds hand and waterproof rating, and offered it on either a strap at $89.50 or a bracelet at $95.00. The K-456 is closely related to the Automatic K-455 and the Rotomatic I, all sharing the same basic direction in Hamilton's mid-1950s automatic lineup.
Finding one in honest condition means looking closely at the dial first. Hamilton specified 18K gold numerals here, which is a meaningful detail, and originals should have that warmth and weight to the applied figures rather than replacements that sit flat or show discoloration around their edges. The waterproof designation was accurate for its era but means nothing for actual water exposure today, so any example that shows case corrosion or a fogged dial has likely seen moisture at some point.
From the Catalog
Hamilton's 1956 catalog described the K-456 as a 10K yellow gold-filled case with stainless steel back, featuring 18K gold numerals and luminous dots, and carrying a waterproof rating. It retailed at $89.50 on a strap or $95.00 on a bracelet.
Hamilton Catalog Images
1956
1957
1958
What to Look For
| Dial | Look carefully at the applied gold numerals. Hamilton specified 18K gold for these, and originals have a distinct warmth. Replacements or redials often show glue residue, misalignment, or a different color tone around the feet. Also check for any darkening or burning near the center of the dial, which can happen from hands sitting in contact over decades. |
| Crystal | Check for deep scratches or crazing. A worn crystal is inexpensive to replace, but confirm the seller is not pricing the watch as if the crystal is fine when it visibly is not. |
| Movement | Ask about service history. The caliber 661 is an automatic, and oil that has dried and thickened over years of sitting can build up enough friction to stop the movement entirely. A watch that winds by hand but will not wind automatically is often a rotor or winding mechanism issue, both of which should be disclosed. |
| Case | Examine the case back for pry marks. On some Hamilton models from this era, the case opens through the crystal side rather than the back, and uninformed attempts to open it from the rear leave visible damage. Also check the gold-filled surfaces on the case for wear-through to the base metal, particularly on the lugs. |
| Crown | The waterproof designation on these watches does not translate to actual water resistance today. A crown that feels loose or screws down improperly should be noted, as that is often the first point where moisture enters an otherwise intact case. |
The Movement
The caliber 661 is Hamilton's 17-jewel automatic, a self-winding movement that winds the mainspring through the motion of the wrist via an oscillating rotor. It runs without a manual winding habit required, though it can also be wound by hand through the crown. For its era it was a reliable and well-built movement, though like any automatic that has sat for years, it benefits significantly from fresh oil and a proper service before daily wear.