How thick is 25 years gold filled?

[Mr_Smurf]

How thick is the gold layer on a 25 years gold filled watch from sometime early 1900?

[Mr_Smurf]

How thick is the gold layer on a 25 years gold filled watch from sometime early 1900?

[Kent]

Approximately thick enough to last about 25 years.

Kidding aside, I don't believe that there is any watch case company data that states just how thick the gold was on their cases. There certainly wasn't any standard for it. The best I can do is a case guaranteed to wear permanently (not just for 25 years), Illinois' “Elgin Pride (http://photos16.flickr.com/19807185_3b823d0f73_o.jpg)” which was 1/4 gold (25% of the weight was gold).

Good luck,

[RON in PA]

Due to this confusion I believe that sometime around 1924 the US government mandated that watch case manufacturers stop marking cases with "year" guarantees and instead start marking with type of gold alloy (18k etc.) and gold filled or rolled gold plate.