Thinline 6512
1968–1970 · 10k Rolled Gold Plate / Stainless Steel · Manual Wind
About the Thinline 6512
The Thinline 6512 appeared in only one catalog year, 1968, as part of Hamilton's Thinline family, a line built around slim profiles and clean dress aesthetics that defined much of Hamilton's late-1960s output. The round case is 10K yellow Rolled Gold Plate over stainless steel, with a white dial carrying applied gold numerals at all positions and a subseconds register at six o'clock. Power comes from the manually wound caliber 639, a 17-jewel movement Hamilton used across several of its dress watches during this period.
Applied gold numerals on a vintage white dial can oxidize unevenly over decades, so it's worth looking closely at how well the numerals have held their finish relative to the dial surface. The 6512 was offered with either a bracelet or a strap at two different price points, so original bracelets, if present, are a nice bonus but shouldn't be assumed.
From the Catalog
Hamilton listed the 6512 in 1968 with a 10K yellow rolled gold plate top, priced at $49.95 on a strap or $59.95 on a bracelet, positioning it as an accessible dress option in the Thinline range without crossing into the higher price tiers Hamilton reserved for solid gold cases.
Hamilton Catalog Images
1968
What to Look For
| Dial | Look carefully at the applied gold numerals, each one is a separate piece and can pull away from the dial, shift, or show tarnishing independently of the dial. Check that all twelve are present, seated flat, and that the white dial surface itself hasn't yellowed or developed uneven patina around the numeral footprints. |
| Crystal | The crystal on a watch this age has almost certainly been replaced at least once. Make sure the replacement fits the case correctly, an ill-fitting crystal can look fine at a glance but may not seat properly against the bezel. |
| Movement | The caliber 639 has very little clearance between its overlapping parts, and oil in a movement this age has almost certainly dried out. Dried lubricant creates enough friction to affect timekeeping noticeably, or stop the movement entirely. Ask whether the watch has been recently serviced and by whom. |
| Case | The case back on rolled gold plate models can be stubborn to open without the right tools, and improper opening attempts often leave marks on the case back edge. Inspect that edge closely. Also check the RGP layer on the lugs and case sides, high-wear areas where the gold plate thins first. |
| Crown | Pull the crown gently through its positions and feel for smooth engagement. A crown that feels loose or sloppy can indicate a worn stem or a damaged set lever, the set lever tip is a known vulnerability on this caliber during stem removal. |
The Movement
The caliber 639 is a manually wound, 17-jewel movement that Hamilton used in a number of its slim dress watches during the late 1960s. It winds, sets, and runs with a straightforward hand-wind interface, but the movement's close internal tolerances mean it rewards careful servicing, dried oil or debris has less room to be forgiven here than in a more open-structured caliber.