Thinline 2021
1966–1967 · 14k Solid Yellow Gold · Manual Wind
About the Thinline 2021
Made from 1966 through 1967, the Thinline 2021 is part of Hamilton's Thinline family, a line built around the appeal of slender, elegant rectangular cases in precious metal. The movement inside is the caliber 680, a 17-jewel manual wind movement that Hamilton paired with this ultra-thin case profile to deliver a watch that could sit low on the wrist without bulk. The 14K yellow gold case houses a square silver dial with applied gold hour markers and a subseconds register at 6 o'clock.
Finding a Thinline 2021 in good shape means paying close attention to the case, since 14K gold wears differently than steel and decades of polishing can soften the original lines. The applied gold markers on the dial are also worth scrutinizing up close, as any that have shifted or come loose will affect both the look and the value.
From the Catalog
Hamilton marketed the Thinline 2021 in 1966 at $175, emphasizing its ultra-thin case design alongside practical features including shock resistance, anti-magnetic construction, and an unbreakable mainspring. The watch was listed as waterproof and dustproof with seals intact, though as with any vintage watch of this age, that rating should not be relied upon today.
Hamilton Catalog Images
1966
What to Look For
| Dial | Look closely at the applied gold hour markers. Each one should sit flat and evenly spaced. Any that are separating, shifted, or missing will be difficult and expensive to correct. Also check the silver dial surface for spotting or foxing around the edges, which is common on dials of this age. |
| Crystal | Check for deep scratches or chips on the crystal. A hazy or heavily scratched crystal can usually be replaced, but confirm the correct profile is available for this case before buying. |
| Movement | Oil in the caliber 680 dries out over decades, and a movement that has been sitting can have enough friction built up to run erratically or stop entirely. Ask about service history, and budget for a full service if that history is unknown. |
| Case | The 14K yellow gold case is soft by nature and will show wear over time. Look at the lugs and the edges of the case for signs of over-polishing, which rounds off the original geometry. Some wear is expected, but a case that has been repeatedly buffed will have lost its crispness. Case backs on watches like this can be difficult to open, so check for signs of damage around the case back edge from improper tools. |
| Crown | Test the crown through winding and setting. It should engage smoothly and the stem should have no wobble. A loose or damaged crown on a gold case watch can be a bigger repair than it looks. |
The Movement
The caliber 680 is a Swiss-made 17-jewel manual wind movement that Hamilton used across several of its Thinline models during this period. It is a straightforward, reliable movement designed to run slim enough to suit the thin case profiles Hamilton was emphasizing in the mid-1960s. Servicing it requires care, particularly around the mainspring and escapement, but parts availability is reasonable and a competent watchmaker should have no trouble with it.