Thin-o-matic T-407
1963–1965 · 10k YGF · Automatic
About the Thin-o-matic T-407
Made from 1963 through 1964, the Thin-o-matic T-407 runs on Hamilton's caliber 620 automatic and wears a 10k yellow Gold Filled round case with a silver-toned gold dial and stick markers. The sweep seconds hand and slim profile put it squarely in the Thin-o-matic family, Hamilton's line of slender automatic dress watches built around the compact caliber 620 micro-rotor movement. It was offered both on a strap and on a bracelet, with pricing starting at $85 in 1963.
Finding a T-407 in solid shape means looking closely at the dial finish, since the silver ground on these can show age spots or discoloration near the edges where moisture found its way in decades ago. The Gold Filled case holds up reasonably well, but check the lugs and caseback edges for wear-through to the base metal, which is common on pieces that saw daily use. The hidden lug design gives it a clean, integrated look that can make finding the right strap a small puzzle.
From the Catalog
Hamilton marketed the T-407 simply around its 10k yellow gold filled case, offering it on a bracelet for $95 or on a strap for $85 in 1963, making it an accessible entry point into the Thin-o-matic line at the time.
Hamilton Catalog Images
1963
1964
What to Look For
| Dial | Look for spotting, fading, or separation near the dial edges. The silver finish on these can develop age spots, particularly around the perimeter. Stick markers should be crisp and lying flat. |
| Crystal | Check for deep scratches or crazing in the crystal. A fogged or crazed crystal can be a sign of moisture intrusion, which is worth investigating before assuming the dial underneath is clean. |
| Movement | Ask when the caliber 620 was last serviced. Oil in a movement this age thickens and loses its ability to lubricate properly, which creates enough drag to stop the movement or shorten power reserve significantly. This caliber also has a micro-rotor that can ride up its axle and rub against the caseback, so listen for any faint grinding sensation when you move the watch. |
| Case | Inspect the lugs and caseback edges for wear-through on the gold fill. These cases see more wear at the contact points, and once the base metal shows, it tends to spread. The hidden lug design makes this harder to spot at a glance, so look carefully. |
| Crown | Work the crown through its positions. It should set the time smoothly without slipping. Any roughness or looseness at the stem could point to a worn crown or a setting lever that needs attention. |
The Movement
The caliber 620 is Hamilton's American-made micro-rotor automatic, running at 17 jewels. Instead of the full-sized rotor that sweeps the full diameter of the movement, the 620 uses a small weighted rotor mounted flush within the movement plate, which is what allows the Thin-o-matic line to stay so slim. It winds in both directions and keeps a tidy, dress-watch profile under the caseback.