Was wondering if the size of 8 reale coins minted in Mexico City could be different from coins minted in Potosi Bolivia ? I have around 6 8 reale Mexico City coins and one Potosi coin . The weight of the Mexico City coins is 26.96 g and the Potosi coin is 26.53 g . If laid on each other the potosi coin is about 1/64 “ longer . Thoughts ?
I believe that all of these have a slight varence... just like cobs "pieces of 8" were cut for two reasons to stay within 27/28 g. Or cut to make change....due to lack of smaller coins
Although I don't have any measurements, or side-by-side photos at hand, I will say that after many years of collecting 8 reales, the ones minted in Potosi (Bolivia) are often noticeably wider in diameter. I think the weights are about the same as the Mexican and Peruvian 8 reales, but they are wider. I'm pretty hazy on how coins are minted, but I imagine it has something to do with the collar setting, or the mint machinery in general. Some of the earlier portrait types from Peru (Lima) also share this broad-flan look. The very first 8 reales I ever bought, in 1987, is from Potosi (Bolivia). Photo below. Notice the area of weakness on the reverse by the right pillar/lower castle area; this is very common on the Potosi 8 reales I've seen - as if not enough metal was available to fill in all the details. The letter on these have a kind of spaced-out look too. After you've handled a few of these, you get kind of a "feel" for the difference. Or else I'm deluding myself - it wouldn't be the first time!
Exactly what I thought . Since it’s struck in an open collar it would depend on how they set it and pressure used . I was wondering if the castaining machine , the machine that puts the edge design on , would have to be set a little wider too . But the weights are within tolerance on both the Mexico City and Potosi coins . Thanks for your answer Mike ! I also tested it for silver which it is . It was bought in the late ‘50s to ‘60s at Carson Pirie Scott back when they sold coins . So I imagine it was approved by their coin experts ! How expert they were I have no idea .
1792 assayers are PR https://www.ngccoin.com/price-guide/world/bolivia-8-reales-km-73-1791-1808-cuid-1065351-duid-12750468
When you're talking about the Spanish colonial coins you have to pin things down by date to know how they were struck. Milled coinage did not begin until 1773 in Mexico City, the other mints changed at various times a bit later. Prior to 1773 the edge design was put on the coin by an edge die - the coin was physically rolled through the edge die. In and after 1773, that's when collars were used. As for the weight and tolerances, you can read about that here - https://www.cointalk.com/threads/weight-range-for-spanish-8-reales.238204/#post-1810029 The diameter, yeah prior to milled coinage it was quite common for the diameter to vary slightly, or more than slightly, in different mints and within the same mint. But once milled coinage began the diameter became much more consistent. Maybe not exact all the time but much more consistent.
Depends on the period. Cobs (hammer struck) varied widely in terms of flan size and shape. Milled coinage, on the other hand, had some variation in flan size, but within narrow parameters. A typically irregular 8 reales cob of 1626P, Potosi, Bolivia: A "round" 8 reales cob, Potosi, Bolivia, 1746q: A milled 8 reales, Potosi, Bolivia 1791PR, broad flan:
I'm assuming that is a typo in your reference date of 1773 for the introduction of collared dies at Spanish colonial mints as I have many examples from 1773 to the end of colonial issues that show clear evidence of edging on a parallel edging and upsetting mill and not from a collared die. Bob Gurney mentions that this process, even after mechanization, continued until 1897.
