Thinline 6504
1968–1969 · 10k Rolled Gold Plate / Stainless Steel · Manual Wind
About the Thinline 6504
The Thinline 6504 appeared in the 1968–1969 catalog. Part of Hamilton's Thinline family, it shares that line's focus on slim, clean designs suited to the late-1960s taste for understated dress watches. The case is cushion-shaped, made from 10K yellow Rolled Gold Plate with a stainless steel back, and the movement inside is Hamilton's caliber 639, a 17-jewel manual wind. The dial is silver with a subseconds register at 6 o'clock and applied gold numerals at 12 along with applied gold markers throughout.
Dial condition is the first thing to check on a 6504. The silver finish can show spotting or moisture damage near the subseconds register, and the applied gold markers are small enough that one missing piece is easy to overlook in photos. A pearlescent dial variant exists alongside the standard silver, so if the listing photo looks iridescent rather than flat silver, that is not damage but a legitimate alternate version worth confirming.
From the Catalog
Hamilton listed the 6504 in 1968 at $49.95 on strap and $59.95 on bracelet, positioning it as an accessible entry point in the Thinline lineup. The catalog copy kept it brief, noting the 10K yellow RGP construction without much elaboration, which was typical for the more modestly priced pieces in that year's collection.
Hamilton Catalog Images
1968
What to Look For
| Dial | Look closely at all applied gold numerals and markers under good light. The 12 numeral and surrounding markers are small and the feet that hold them to the dial can loosen over decades. Check the area around the subseconds register for any discoloration, bubbling, or moisture staining. If the dial has a pearlescent quality, confirm whether that matches what the seller is describing. |
| Crystal | The cushion case shape means the crystal follows an uncommon curve. Check for cracks at the corners where stress concentrates, and look for deep scratches across the face that a flat crystal swap would not fix correctly. |
| Movement | The caliber 639 has very little clearance between its overlapping parts, which makes dried oil a real problem. A movement this age that has not been serviced in many years may stop intermittently or run inconsistently even if it winds and sets without complaint. Ask about recent service history before assuming it is running well. |
| Case | The RGP layer on the top of the case will show wear over time, most visibly on the lugs and any high-contact edges. Check those areas carefully in photos and ask about the depth of wear. The case back is stainless and should be in better condition, but case backs on watches of this era can be stubborn and are sometimes damaged by improper opening attempts. |
| Crown | Wind the crown slowly and feel for roughness or slipping. A smooth, consistent wind is a good sign. The set lever tip on the 639 can break during stem removal, so if the crown pulls out roughly or not at all, that is worth flagging before purchase. |
The Movement
The caliber 639 is a 17-jewel manual wind movement built by Hamilton. It is a compact movement designed for slim cases, which accounts for the tight tolerances between its parts. Those tight tolerances also mean that worn or dried lubricants have an outsized effect on how it runs, so a proper service with correct oils makes a meaningful difference in timekeeping.