Hi
I don't think that clipping was ever a great problem with Greek and
Roman coinage because of the relatively thick flans and naturally rounded edges which would have made any attempts to clip rather obvious.
Once you get to the smaller siliquae the
flan is thin enough to clip easily, but there
still doesn't seem to be much of a problem except in
Britain, where they are regularly clipped in the 380's-420's (I don't think any one is sure of the date, so I leave a wide range). Whether this was to reduce existing coins to a new lower
weight standard or as a source of profit for the holders of the coin is also uncertain, but the
weight standard adjustment was probably the main impetus, and of course people will have taken advantage of this to make a profit where they could.
Thin
Byzantine silver (eg miliaresia) is clipped, and even some of the
billon trachys, and wherever there was a chance to nibble a little profit off the edge of a thin coin, someone will have done it.
Sasanian silver is sometimes clipped, though again this can be partly an attempt to reduce the
weight from the c.4.2 gm
Sasanian standard to the c.3.8 gm Arabic dirhem
standard.
Mediaeval european coinages are mostly thin, and therefore easy to clip, so people clipped them, and clipping becomes epidemic in
England in the 16th century, just when Shakespere was
writing.
I think it boils down to the fact that, where it is easy to trim a
bit off a coin without the fact being too obvious to the person you are going to pass it to next, then there is the temptation to do so. The physical form of Greek and
Roman silver and gold make this diffucult, so it will not have been a major problem. A thin spread
flan is easy to trim a
bit off, and the irregular centring and spread of most hand-struck thin coins means there is often a little piece outside the edge of the design which can be trimmed without it being noticeable.
Also, as a coinage begins to be more passed by
face value rather than being check weighed at each transaction the temptation will increase. The weight-difference is too small to be noticed just having the coin in hand. If I remember rightly, at the time of the Great Recoinage in
Britain in the 1690's some of the bags of old coin brought in to the officials for recoinage were up to 50% underweight (I'll check this when I get
home tonight), but were accepted at
face value, the difference being made up by the Government by taxation, notably the Window Tax.
Anyway, enough of a ramble
Best wishes
Alan