Dateline T-678
1966–1967 · 10k Rolled Gold Plate · Automatic
About the Dateline T-678
Made from 1966 through 1967, the Dateline T-678 is part of Hamilton's Dateline family, which built its identity around automatic movements with date or calendar functions at accessible price points. This model runs on the caliber 621, a 17-jewel automatic, housed in a 10K yellow Rolled Gold Plate case with a circular profile and swept lugs. The silver dial carries embossed gold numerals at 6, 9, and 12, with embossed gold markers filling the remaining positions and a sweep seconds hand completing the layout.
Embossed numerals and markers hold up better than printed ones over time, so the dial on a T-678 tends to age gracefully when it hasn't been mishandled. Finding one in honest, unpolished condition with the original bracelet intact is increasingly difficult, since most examples surface on replacement straps with cases that have been buffed flat.
From the Catalog
Hamilton listed the T-678 at $110 on a strap and $110 on a bracelet in 1966, positioning it as an approachable entry into the Dateline automatic lineup with a dressed-up but wearable character.
Hamilton Catalog Images
1966
What to Look For
| Dial | Look closely at the embossed numerals and markers. They should be crisp and sitting flush, with no separation, cracking, or signs of moisture damage. Check the silver finish for haziness or spotting near the center, which can indicate the watch was exposed to water at some point. |
| Crystal | Check for deep scratches or chips. A foggy or crazed crystal can obscure the dial underneath, so try to view it at multiple angles before assuming the dial condition is what it appears to be. |
| Movement | The caliber 621 is an automatic, and dried lubricants are common in any movement this age. Give the watch a gentle wrist movement and watch whether the sweep hand runs smoothly and consistently. A watch that stops and starts erratically often points to friction in the rotor or mainspring, both of which need attention from a watchmaker before the watch is reliable. |
| Case | This is a rolled gold plate case, so inspect the high-wear points on the lugs and case back edge for areas where the plating has worn through to the base metal. Light surface wear is expected, but deep brass showing through affects both appearance and long-term durability. |
| Crown | Work the crown gently through its positions. It should engage cleanly and wind without grinding. A loose or wobbly crown often means a worn stem or stripped setting, and on a watch marketed as weatherproof, a compromised crown seal means the water resistance is gone entirely. |
The Movement
The caliber 621 is a 17-jewel automatic movement that winds itself through the motion of the rotor as the watch is worn. Hamilton used this movement across several of its mid-1960s automatic models, and it is a solid, if somewhat compact, workhorse. One known characteristic of the 621 is that the oscillating weight can develop slop on its axle over time, which reduces winding efficiency and, if left unaddressed, allows the weight to contact the case back.