D in a diamond almost certainly predates 1928, the mark can be found on quite a few BIM bottles and I'm pretty sure those weren't being produced much in Canada by 1928.
I'm not sure when the mark was first used but I would assume it was not long after Dominion was formed in 1913. I know that the internet says the mark was first used in 1928, but this is almost certainly an example of one person getting it wrong and everyone else repeating the same information afterwards. The 1928 date originated with this quote from Thomas King's 1987 book Glass in Canada: "about the same time, a family had established a distillery in the Province of Saskatchewan. Made under normal conditions, their product was far superior to that produced illegally in the American “stills.” As a result, and with some international connivance, their superior product was appearing in unmarked bottles in the mid-west United States. However, it was too good to last, and about 1927 the American authorities required that all glass containers entering the United States from Canada have embossed on them the country of origin. As a result, the company [i.e., Dominion Glass Co.] adopted the Diamond Dtrademark." This is, frankly, nonsense, and I can't understand why Bill Lockhart accepted it uncritically when he repeated it in his SHA article. Several things are wrong with this quote: 1. A logo is not a country of origin. 2. The illegal liquor was being smuggled illegally, so who cared about labelling requirements? 3. The Americans knew that the illegal liquor was coming from Canada, it usually said so on the label and anyway, Canada was known as the country with all the liquor. Why would they care where the bottles were being made, and why would anyone follow this law?
