TL; DR:
As an example, the French manufacturer Couesnon had a bunch of different saxophone models available at the same time in the late 19th century.
US-made saxophone stencils and second-line horns appeared in the early 1920s and, as far as I can tell, starting with Conn.
I don't think I've seen any gold-plated or silver body with gold-plated keywork on any second-line horn or stencil from the US.
There were a lot of finish choices available on Conn and Buescher pro horns. Somewhat fewer choices for other US manufacturers.
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I'm only talking about US-made horns, below. I think you could successfully argue that
Evette-Schaeffer and/or
Couesnon had "non-pro" lines as early as the late 19th century, as both offered models with reduced keywork and at a lower price than their high-end models. Also, Couesnon, E-S, and Kohlert all produced stencils prior to the 1920s. (I mention more about stencils, below.)
Here's a page from my old website regarding Conn finishes. There were a lot. Buescher had similar finish choices, except for the additional pearl keytouches found on the Conn Virtuoso Deluxe finished horns. A brief look at my Martin Handcraft picture archive shows only a couple horns that were silver body with gold keywork. Same with my HN White King archives. I've seen gold-plated Yorks and Holtons. I don't think I've seen any gold plate Couturiers, but there were probably some. So it's possible that all your US manufacturers at least had bare brass, nickel, silver, silver body with gold-plated keywork, and full gold-plate.
I've seen several horns that have been re-finished with a silver body and gold plated keywork and vice-versa. I've also seen a number of horns that have plating that's so worn, the brass peeks through the silver plating to make them look like two-tone finishes, but if you look closely you can see the wear.
The Conn Pan American line was not exactly considered a student or intermediate horn, but just a second line of horns that was usually made using completely different construction than their pro line. This is easily evidenced by seeing a different patent number stamped on P-A saxophones. After Conn started their second line, Buescher, Martin, and HN White started their second lines. Holton's a bit of a special case. I'll get to that in a minute.
There's also something known as a
stencil. A stencil is a horn made by one company for a storefront or other outlet. The storefront gets a horn that has little to no engraving, puts a stencil of their own design on the bell and starts engraving. Most American-made stencil saxophones either lacked features that the pro model had (in Conn's case, no rolled tone holes) and/or were made with older tooling (Buescher). Conn also made stencils of their Pan American horns, so it gets confusing really quickly.
I mentioned that Holton was special. I don't have my full time line in front of me, but suffice it to say that there was an interesting relationship between Holton, Couturier, and Lyon & Healy. So, you'd see some Lyon & Healy Horns that were made by Holton or Couturier that aren't stencils in the traditional definition. Also, Holton made some horns for Gretsch that didn't look at all like their own (Holton's own) pro line.
Anyhow, the patent date on "true" Pan Americans is 1917. I've owned Conn stencils from the early 1920s. Both of these would be considered less than a Conn New Wonder pro horn from about the same time.
I'm fairly sure that I have
not seen either gold-plated horns or silver plated horns with gold-plated keywork from ANY US-made stencil or second line. However, do note that I've not been in the habit of collecting stencil pics. I think that if those high-end plating choices exist on any stencil, you'd find it on the (usually) Conn-made Selmer NY horns.
