In ancient Chinese numismatics, there are sometimes coins that show a link between one coin type and another. They are usually quite scarce, but they do show up from time to time. I was just notified that I one my second example of a coin in this category: a knife coin that shows the transition between pointed knives and Ming knives. (My first is a spade, and I will show it in a later comment.) The earliest knife coins are called “pointed knives” because they often had a pointy end like a real knife, as well as being structurally similar to a real knife. These would have a reinforcing ridge on the back to increase the strength of the coin, like an actual knife would. However, this would be phased out within a hundred years for a simple flat design, presumably to make the molds easier to manufacture. The rims on my specimen are all the same height and carved the same way. Here is the coin I bought. You can see how it clearly has the elements of the above pointed knives, yet it differs significantly from the two Ming knives posted below. For one, the rims are thin and short, which is characteristic of the later pointed knives. Other differences include a more-curved blade, a large, round Ming, and just an overall different style. Yet it has the Ming character on the obverse, as well as another character on the reverse, meaning it is definitely related to the later Ming knives. It is not a Boshan knife because those are characterized by large, angular Ming. This coin has a curved ming, like the later (but early) Ming knives. Coming from these prototype Ming knives, the Yan state refines the style of its knives by casting everything in heigher relief and with thicker strokes. The earliest coins of this style have a smaller, yet round, Ming and a curved back, like on the pointed knives. Then for some reason the Yan state decided to make their knives straighter and more angular. This type is characterized by a sharp angle between the handle and the blade, a straight handle and blade, and a squat Ming that looks like an eye. This design was frozen and was pumped out for decades until the Yan state fell to the Qin. Some comments: These transition pieces are extremely difficult to come by. I have not seen one come up for sale for as long as I have been collecting, so I doubt I will see more than a couple more in the next decade. Due to their scarcity (and the middle-style curved-back Ming knife is not all that easy to find) the transition must have been quite rapid. When I get back to the US, I will dig more into this and see if I can find a reason why the transition happened as rapidly and as radically as it did. But when the angled-back version was adopted, that design was continuously mass-produced with little to no change until the coinage ceased entirely. This makes the angled-back Ming knives the most common type of ancient Chinese not-round coins by far. Here is an interesting picture I found (likely from a Chinese museum) which shows and much-more gradual transition than as seen with my coins. You can see how the Ming character, the shape, and the rims evolve from bottom to top.
And here is the transition spade, and you can easily see attributes of the pointed-foot spades and the square-foot spades.
