Two 28cm sauté pans, both alike in dignity…
… but compare their measurements.
28cm by 8.1cm
3.3mm at the rim
4602g (10.2 lbs)
28.5cm by 7.9cm
2.6mm at the rim
5354g (11.8 lbs)
The vintage pan measures 3.3mm at the rim, .6mm thicker than the antique pan, and yet the antique pan weighs a pound and a half more.
How can that be? Well, to paraphrase, it’s all about that base. Pans made in the 19th century and in the early 20th can be thicker in the base than up the sides, sometimes by a couple of millimeters. This unevenness is not a bad thing and can even provide a benefit for stovetop cooking — the floor of a pan is its primary cooking platform while its sidewalls play a lesser role. Gaillard, for its part, made no bones about the fact that its pans were thicker in the base than in the sides and provided cutaway images in their catalogs to show it.
Would you have known just by looking at the two sauté pans above that the one on the right was so much heavier? This is why weight matters: it can often tell you more about the quality of a pan than measurements at the rim. Copper thickness predicts how a pan will perform when you cook with it, and in many cases correlates to the worth of a piece. (In fact, I calculate the price paid by weight for each piece in my collection so I know which ones have been the best value.) Rim thickness tends to be more reliable for pans made after WW2, in my experience, but for a 19th or early 20th century pan you should get the pan’s weight as well and compare it to others of known uniform thickness. (I’ve put together a bunch of data tables if you need reference values.)