Edges on Coins

        Probably more than three-quarters of circulation coins across the world have either plain or milled edges. Usually the smallest denominations have plain edges and the higher denominations will be milled, except in the case of multi-sided coins which are often with just plain edges for simplicity of manufacture.
    The use of edge milling was first introduced on higher value coins to make it easy to know if some precious metal had been filed from the edge of a coin. Even today very few gold coins have plain edges. In modern times one very useful reason for this feature is to help those with impaired vision distinguish between one denomination and another. The use of fine and coarse reeding is often to help with this too.
        The milling itself can vary between different coins in a few ways other than the obvious fine and coarse varieties as already mentioned. The shape of the milling (the shapes of what one might call the crest and trough) can vary, the two basic varieties are those with square troughs and those with vee-shaped troughs. These variations are only of interest when coins are known that differ only by such a feature. Another variation on the milled edge is that with slanted serrations, slanting to the left or to the right, another is where the serrations intentionally do not reach from one side to the other of the coin’s edge. These two variations on the milled edge theme are very seldom, if ever, encountered on coins of the last hundred years or so and they are therefore of little interest to me.
        That still leaves hundreds of world-wide coin types with something other than a plain or a simple milled edge. These other edge types are usually used for reasons of either increased security or increased aesthetics. A simple combination of plain and milled edge can be found on coins with what is known as an interrupted milled edge. These have a certain number of equally spaced milled sections on an otherwise plain edge.
        The most common additional feature to an edge other than milling (or serrations) is, of course, edge lettering. This can be either incuse or raised. Edge legends are often mottoes or country names, some even include dates. Combining standard edges with the two basic type of lettering we could have four possibilities these are:- (a) incuse lettering on plain edge, (b) raised lettering on a plain edge, (c) incuse lettering on milled edge and (d) raised lettering on a milled edge. Well common sense makes one realise that last possibility (d) is not really practical. The nearest we get to (d) is with edges where the milling is interrupted with plain sections that have on them raised lettering.
        A more sophisticated adaptation of the milled edge is the security edge. These are used by quite a number of countries throughout the world and have a groove along the central line of the milling around the circumference of the coin. This groove usually has a pattern of raised lines and dots along it. A special case of the security edge is that found perhaps only on a few types of 5 Dollar coins of Hong Kong. These are quite thick coins and the groove around the otherwise milled edge has in it, raised edge lettering.
        Earlier I mentioned multi-sided coins. These seldom have any edge milling. A few do though and in such case the milling is applied only to the middle section of each edge. Very few multi-sided coins have edge inscriptions. In fact perhaps the only ones are some 50 Pence coins from the Isle of Man that were made by the Pobjoy Mint around 20 years ago. These pieces have incuse lettering on otherwise plain edges. I do not know of any scalloped edge coins with anything other than plain edges. This would, no doubt, be quite a difficult thing for a mint to achieve. Furthermore it seems that lots of recent scalloped edge coins are of lower denominations.
        Other things to be said about an edge are more to do with shape. For example “chinks” of regular shape can sometimes be seen in the edges of coins. The recent 50 Peseta coins of Spain are an example of this. “Chinks” in the edge make the otherwise circular coin a shape known as “Spanish Flower”. The future 20 Eurocent coins will have this special shape too.
        Finally, a few other things to see on the edge of a coin.
        A few coins with edge inscriptions include a mint mark within the inscription. The current British 1 and 2 Pounds coins have on their edges the “cross crosslet” mint mark of the British Royal Mint.
        Normal milled edges are applied during striking, the coin when hit by the force of the press stretches outwards from the centre and into the collar around the planchet. If this operation goes wrong the milled edge will be malformed. Such pieces are called broad-strikes and often have an amount of the milling missing.
        Edge lettering, it seems, is most often done separately to striking since most coins with edge lettering occur in two varieties. Looking at the edge letterring on a coin with the lettering upright you will see either the obverse or the reverse on top of the coin. These two varieties for a particular coin will most often appear in similar numbers as one another, so we know that which way up a planchet with a lettered edge lands under the press for striking is left to chance and nothing else. You just might be thinking that these two varieties come about because sometimes the upper die is that for the obverse some days and that for the reverse other days, however this arrangement is believed to be kept very constant.
        I reckon that before long some new innovation will come about for coin edges, either through the need of a mint to increase sales of their collector coins or for them to increase the security of their products (i.e. improve anti-counterfeiting properties). Only time will tell.