"Gold stainless steel" Apple watches series 8-9: how are they made?

Can anyone comment on the manufacturing process of the newer Apple watches "Gold" stainless steel cases? Back in 2015 when the first series came out, the gold cases were solid 18K gold. But now? I saw a YouTube video (made by Apple) that explained the manufacturing process of the new graphite stainless steel cases. How about the new gold-colored cases? I expect they are electroplated and therefore will start fading around the corners in a couple of years.