Thinline 6505
1968–1970 · 10k Rolled Gold Plate / Stainless Steel · Manual Wind
About the Thinline 6505
Made from 1968 through 1970, the Thinline 6505 is part of Hamilton's Thinline family, a line built around slimmer profiles and cleaner aesthetics that defined much of Hamilton's late-1960s American catalog. The case is 10K yellow Gold Filled with a stainless steel back, round in shape with swept lugs, and it runs the caliber 639, a 17-jewel manual wind movement. The dial is white with applied gold markers and no printed numerals, keeping the look minimal and spare. A subseconds hand sits at the 6 o'clock position.
Applied gold markers on a white dial are prone to separation at the edges or showing discoloration where moisture has crept beneath them over the decades, so inspecting the dial closely matters on any example. The 6505 was offered both on a strap and on a bracelet, so the bracelet configuration turns up occasionally and is worth identifying, since it changes the original retail price. Gold Filled cases from this era can show wear through to the base metal at the lugs and bracelet attachment points, which is worth checking before buying.
From the Catalog
Hamilton listed the 6505 in 1968 at $49.95 on a strap, with a bracelet configuration available at $59.95. The catalog entry describes a 10K yellow gold-filled top with a stainless steel back, which reflects the practical approach Hamilton took with much of the Thinline lineup during this period.
Hamilton Catalog Images
1968
What to Look For
| Dial | Look carefully at the applied gold markers under magnification or good light. Separation from the dial, corrosion at the base, or dark halos around the feet are common on white dials of this age. The white dial finish itself can develop uneven patina or small spots if moisture ever got inside the case. |
| Crystal | Check for deep scratches or crazing in the acrylic crystal. A hazy or heavily scratched crystal is easy to replace, but confirm the replacement is the correct diameter so the fit is right. |
| Movement | The caliber 639 has very little clearance between its overlapping parts, which makes dried oil a real problem. If the watch has not been serviced recently, assume the lubricants have hardened and are creating friction throughout the gear train. Ask about service history before buying. |
| Case | Examine the lugs and case edges for wear through the gold-filled layer. On 10K RGP cases this old, the plating at high-contact points often shows brass or base metal. Case backs on these models can be difficult to open without the right tools, so avoid examples that show pry marks around the back edge. |
| Crown | Work the crown gently through its positions and confirm it winds smoothly and sets the hands without slipping. The stem can be fragile during removal, and a broken set lever tip is a known issue on the 639 if the stem has been forced. |
The Movement
The caliber 639 is a 17-jewel manual wind movement made by Hamilton in the United States. It winds and sets conventionally, with no quick-set complication, and keeps good time when properly serviced. The tight tolerances in its construction mean that a full service requires patience and care, but a well-maintained 639 is a reliable performer.