As an aside- but still sort of relevant- I saw an advert today for a commemorative coin for the Coronation. It is 99.9% pure gold, ( the advert mentions that sovereign coins aren't that pure) and there are only 2,023 of them. It sells for a couple of pennies under £100.
Then I looked at the days gold price, which was around £52/gram. Going back to the advert, in small print it discloses that this coin weighs in at 0.8 gram. How tiny must this be?
Yep - some so-called bullion coins could be more accurately described as flakes. Seriously, you'd have to lift them on a single finger, and if you sneezed, bye bye!
The purity thing is true enough, Sovereigns are 22 carat gold (91.7%) for durability (they were once circulating coinage after all, albeit for the richest of the rich - and to this day remain legal tender, with a nominal value of one pound (!!!) despite being one of the few British coins with no declared face value).
I'm a (former) coin collector, if that wasn't obvious.