"Hallmark. A hallmark is an official mark or series of marks struck on items made of metal, mostly to certify the content of noble metals—such as platinum, gold, silver and in some nations, palladium."
The different hallmarks stamped onto a piece of gold or silver, etc. can tell you, for example, the maker of the item, the purity of the metal contained in it, the place of its manufacture, and even the year it was made. Indeed, there are entire websites devoted to the identification of such hallmarks; for example, https://www.silvermakersmarks.co.uk/, or https://www.925-1000.com/index.html, as only two.
Looking at hallmarks, you may notice that a significant number of them have a strong resemblance to heraldry. (Well, it's not all that far-fetched; heraldry was designed as identifying insignia, after all!)
Continuing my ramble around the streets of Canterbury, England, I ran across the following sign for Hadfield's of Canterbury, designer of fine jewelry:
It was more than just the shape they chose for their sign (a "heater", or shield shape), it was their hallmark:
Within the octagonal horizontal cartouche bearing the figure of a lion passant.
Lions passant are a fairly common heraldic motif; not as common as lions rampant, of course, but a quick review of "Beast - Lion" in Papworth's Ordinary of British Armorials will quickly turn up quite a number of them.
Is this heraldry? Strictly speaking, no, it isn't. But it is certainly related to heraldry and coats of arms on more than one level, and I felt I had to include it in this review of the heraldry I saw in Canterbury that day.