Good button, but you haven’t shown the face. Is it plain?
The reply by CbG on the thread linked above has it.
The spelling “colour” tells us it was British-made and quality descriptions such as “Treble Gilt” generally appeared during the earlier part of the 19th Century. The raised lettering on backmark puts it no later than the very early 1840s.
After the War of 1812 and the resulting anti-British sentiment in America, many British manufacturers sought to protect/re-establish their export business by removing place names such as “Birmingham” or “London” from their backmarks and replacing emblems such as crowns with “American” eagle emblems. American manufacturers had begun using eagle emblems for patriotic reasons (although they couldn’t compete commercially with mass production from British factories) and so British exporters copied them for a while until the anti-British sentiment died down.
I would guess it to be 1820-ish to 1830-ish
