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what clues/facts make you determine that these examples are "not" real?
The large one is a "Judaea Capta" coin, struck to commemorate the successful extermination of the First Jewish Revolt in 70 AD. As a coin with very strong "Biblical" connections, it's very popular with collectors, and very frequently copied, so that unfortunately makes us suspicious from the outset.
The details on this coin are very porous. Now, porosity can be a result of corrosion on a genuine coin, but it can also be a sign of casting. In this case, I'd lean towards casting, particularly because of the weak area at the bottom of the obverse, where the lettering, pitting and beaded border just fade away into nothing.
Finally the colour - completely unpatinated. To strip the patina down to bare metal like this requires very harsh treatment; this coin should be extremely and uniformly pitted. There are parts of the surface that aren't pitted at all.
For the second coin, it's much more clearly a modern machine-struck replica. The design is rather crude, especially the lettering, and curiously flat. In my experience, such an effect is created when replica ancients are made from designs copied from an old line-drawing or photograph out of a book, rather than from an actual coin. This particular coin is also very round, flat and even - a sure sign of being machine-struck.
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