Sinclair
1956–1959 · 14k Solid Yellow Gold · Manual Wind
About the Sinclair
Made from 1956 through 1959, the Sinclair came fitted with Hamilton's caliber 770, a 22-jewel American-made movement that was new at the time of the model's introduction and represented a step up from the earlier caliber 747. The case is 14K yellow gold in a square profile, measuring 25mm in length with swept lugs, and the dial carries applied gold numerals at 3, 9, and 12 with pearled dots, those distinctive recessed gold holes, serving as the remaining hour markers. The Sinclair is closely related to the Trent, which shares a similar design direction from the same period.
Finding a Sinclair in good shape means paying close attention to the dial, which is where most of the character lives. The pearled dot markers are a period detail that doesn't show up on every Hamilton square case, and any damage to those recessed holes or the applied numerals is difficult to reverse. The 14K gold case holds up well over decades, but the dial surface and its gold work deserve a close look before committing.
From the Catalog
Hamilton's 1957 catalog listed the Sinclair with a 14K yellow gold case, 14K gold numerals, and pearled dots, priced at $115. The pearled dot detail was called out specifically in the catalog description, which signals that Hamilton considered it a genuine selling point of the model rather than a minor finishing choice.
Hamilton Catalog Images
1957
1958
1959
What to Look For
| Dial | Look carefully at the applied gold numerals at 3, 9, and 12, and at each of the pearled dot markers. Separation or damage to the applied indices is a real concern on watches this age, and the pearled dots, being recessed, can accumulate debris or show corrosion at the edges. Any discoloration or spotting on the silver dial surface is worth noting, as refinished dials lose significant collector value. |
| Crystal | Check for deep scratches or crazing. A worn crystal is replaceable, but confirm the replacement fits the square profile correctly, as ill-fitting crystals on square cases can allow moisture ingress. |
| Movement | Lubricants in the caliber 770 break down over decades, and a movement running on dried oil builds friction that shortens its life. Ask about service history, and if the watch hasn't been serviced recently, factor that into your evaluation. |
| Case | The 14K yellow gold case should show honest wear rather than deep gouges or heavy polishing. Aggressive polishing rounds off the case edges and removes the original finishing. Check the caseback for dents or evidence that it's been forced open incorrectly. |
| Crown | Test the crown through its full range, winding smoothly and setting the time without slipping or grinding. A worn crown on a square gold case can be surprisingly difficult to source, so confirming it's in good condition matters. |
The Movement
The caliber 770 is a 22-jewel manual wind movement made in Hamilton's Lancaster, Pennsylvania facility. The higher jewel count compared to earlier Hamilton calibers reflects the company's effort to reduce friction at key wear points, contributing to better long-term accuracy and longevity. It's a well-regarded American movement, and when properly serviced, it runs reliably and holds adjustment well.