The button-backmark "Superior Quality" originated in Britain in the first decade of the 1800s... and has been in continuous usage ever since then. Therefore, if the backmark says nothing but "Superior Quality" it is almost entirely useless for button dating. Two exceptions are: 1- If "Superior Quality" it written in raised-mark lettering, it dates from sometime between approximately 1800 to 1840. 2- If "Superior Quality" is written in "plain block" lettering, it dates sometime between the 1880s and the present. (Note that SCDigginWithAK's 1902-1910 Great Seal button's Superior Quality backmark is written in "plain block" lettering.) Nearly all of the button-backmarks manufactured before 1880 had "serifed" lettering. A Serif is the little prong (or hook, or knob, etc) on the end of a letter's long bars. See the diagram below. Important note for civil war button diggers and collectors: If a button's backmark has "plain block" lettering, the odds are about 99% that it is from sometime after the end of the civil war.