1. Firstly examine the obverse for any obvious differences. In the three examples below the mint mark, the legend and the portrait appear to be approximately the same. Coin wear or die distortion through use can produce some odd effects so unless there is something glaringly obvious it is best not to discount any coins at this stage.
Comparison of Obverse Dies
As the obverse of a coin was the same for all moneyers at a mint, the physical strikers of the coinage would use that die until it was of no further use. The obverse die was attached to the work bench, a blank was placed on top of it and the reverse die hammered down on it. When there was need to produce coinage for another moneyer the only die that needed replacing was the reverse die. At mints where there was a relatively low output, the reverse dies of several moneyers might be used with a single obverse die. The following examples are all taken from coins of the Lincoln Mint where obverse dies were often shared by moneyers.
that the first leg of the letter A is raised higher than usual and at the end of the letter L there is a tiny further pellet. If we could be absolutely certain that both coins had a double barred A the proof would be almost overwhelming. Because the coins have both been struck off centre one coin is strong where the other is weak, so, apart from checking the positioning and size of the pellets, the second sector is discounted. Similarly the fourth sector is of limited use. The third sector, however, is clear on both coins. Again it is clear that the lettering is in the exact same place relative to the pellets and other letters. In this case it can also be seen that the fifth pellet of the inner circle makes contact with the second of the large central pellets it encloses. Case proven!
The reverses, however, look remarkably similar. Can it be shown that the reverses are from the same die? Step 1. An examination of the reverse legend shows that the lettering is spread out in the same way and that both coins have letters that are joined also in the same way. Step 2. Beginning in the inner ring, under the WAL of Walter, count the pellets in each segment. In this case both coins have 7 pellets per segment (7,7,7,7) but this by itself is insufficient to indicate the dies are one and the same. Step 3. Taking each segment in turn, and inspecting each letter in respect to the inner circle of pellets, it soon becomes clear that the W comes in contact with the same number of pellets,
2. Next count the inner ring of pellets starting from the rim of the crown on the right and counting in a clockwise direction until you reach the rim on the left. On most coins the number will be around 33. In this case Coin 1 has 32 as does Coin 3, however, Coin 2 has 33 and so can be discounted immediately.
3. The next step is to count the pellets again starting from the right but this time stop when you reach the V of hENRICVS.
Note the number of pellets passed plus the one it is pointing at and, if the V does not point directly at an additional pellet estimate how far it is towards the next pellet. In the case of Coin 1 the V number is 15.5 ie 15 pellets have been passed and the point of the V is half way between 15 and 16. The same is true of Coin 3 This does not prove that the two coins are from the same die but things are looking hopeful.
N.B Where V does not point directly at a pellet, using 15.25 to indicate a position just after pellet 15, 15.5 (central position) and 15.75 a position to the right of centre is sufficient. If you are more subtle in numbering you run the risk of missing some potential matches due to die wear/distortion.
4. Next repeat the process with the tail of the letter R s which in both cases rest pointing at pellet 8 and 22.25 respectively.
Giving us a high degree of certainty.
5. The penultimate step is to examine the crown or rather the segment of the inner ring just above the crown. The die sinkers often created variations here. Again both coins have a single pellet to the left of the central fleur and a blank to the right. So that this is easily recalled later, I find it best to record this feature both numerically and pictorially; thus this coin would be recorded •1 + 0• , where the • • represent the end pellets of the crown and the + the central fleur and the 0 shows that there was an absolute blank..
If there had been two pellets to the left and only a wireline to the right it would have appeared •2 + - • or in the case of three pellets either side •3 + 3•
6. After the last stage it would be safe to consider the dies as matching but for those who prefer a greater degree of certainty, it is a case of comparison of individual letter shapes and their positions relative to the pellets of the inner circle. This will be covered more fully in the next section.
Comparison of Reverse Dies
The following example illustrates the importance of die comparison rather well. The two coins illustrated are both of Walter on Lincoln but the obverses have totally different mint marks and further comparison, using the methods outlined earlier, show that the coins have other differences too, so are definitely different dies.
When it is necessary to know whether two or more coins have a common die or dies, it can be a very time consuming business. Equally when a coin is offered for sale it is often frustrating to be faced with the decision of whether to buy, knowing that you may have an identical coin already elsewhere, or whether to leave the coin knowing that it will probably not be there when you return.
This section details how to quickly establish if two coins have the same die and how to record those details so that you can compare that die with others simply from your notes. There is no substitute for having the actual coins in your hand but the following methods will give you a much better chance of success.
The easiest way of comparing dies is to pose the question, “Is there anything that these coins do not have in common?” since if there is any one difference there is no need to go further.