These were produced, according to Conn, from 1932 to 1949. However, I have never seen one with a post-war instrument, and very much doubt these were produced after 1941. As for the start date, none of the catalogs I have seen dating between 1930 and 1941 mention Gold-Tone mouthpieces. Since they most certainly did exist, an actual start date is difficult to determine. Quoting the January 1969 issue of Conn Chord magazine: "Here was a significant departure from early mouthpiece making. The "Gold-Tone" mouthpieces were as much articles of showmanship as they were musical developments. In both appearance and comfort of playing this "Cushion-like" designed mouthpiece had much to offer the jazz bands and big dance bands of the '30's and '40's." (Copyrighted, 1968, By Conn Corp.)
Gold-Tone mouthpieces are known to have existed for cornet, trumpet and trombone. Below is table indicating which number - instrument combinations are known to have existed. Gold-Tone mouthpieces are very rare.
|Conn "Gold-Tone" mouthpieces|
|25||(Very) small cup, wide rim||X||X||-|
|26||Slightly larger than 25, wide rim||X||X||-|
I have found a picture of Benny Carter holding a Conn trumpet (recognizable by the straight braces, looks like probably a 22B) with a Gold-Tone mouthpiece, and Henry Wells playing trombone with a Gold-Tone mouthpiece.
These pictures show a Gold-Tone 22 trumpet mouthpiece from different angles.