You certainly know the Geomatic, one of the most famous Jaeger Lecoultre Chronometer, which took the place of the Geophysic, in 1962. The Geomatic, to make it short, came with two different cases and two different metals. In Steel, Ref E 398: With its fam...
And you are right that the gold version has a more refined case lugs, while the dial also have different variant. Geomatic is a very classic watch and I do like the handset style....the watch rotor is very impressive and have that JL style. Enjoy the hunt...
You can see the SS version has a shorter lug variant and the gold one has much smaller and refined lugs. Maybe other experts have another findings as well.... Just my 0.002 cents.. ...
And the dial has some minor differences in the layout and font but they are very classic and cool watches... The gold versions do have more variants..buckle and dial... I believed the standard 14mm buckle is the correct fit for Geomatic...but I am wrong.....