Why do they all look different? were they individually made at the time?
So, these are three different issues of the same denomination - what we call the antoninianus or double-denarius. They all feature the emperor and legend on the front, and then three different reverses. So they're different because they're three different issues.
But they're also different because they're ancient. Coins at the time were created by hand engraving two stamps/dies, one for the front (obverse) and one for the back (reverse), and then heating a silver disk, placing it between the stamps, and striking it with a hammer. That means all ancient coins are unique, but some may look alike because they're from the same set of stamps.
As time went on, each stamp would be worn down. The uppermost coin was struck using a pretty worn down stamp, as you can see from the washed out details, but still clearly struck; you can see the "flow lines" in the metal pointing outwards from the letters on the back (and front). They're formed when the hot metal exands and are more pronounced on worn dies. At some point a stamp would be too worn out and they'd grab a new one and use that, discarding the old one.
An example of a coin struck with freshly engraved dies is this one:
As you can see, the reverse is super-crisp, whereas the obverse shows a little bit more wear on the letters.
wow, that is fascinating.
this is the first time I've understood how someone can get into coin collecting. every time you get a new coin you must notice the different details, especially with your familiarity with ancient coins.
that is very cool, thank you for explaining the process and the reasons for the discrepancies.
