From my perspective, your coin is authentic. It has the hallmarks: the style of the design elements are consistent with the period; there's graffiti; there's obvious circulation (VF or so); the surfaces, though cleaned, look good; there are no signs of casting, or transfer dies being used. What is the coin's weight? If you want more peace of mind, you could send the coin to David Sear for a certificate. I don't think that is necessary, though. These coins were produced in vast quantities, they were the trade coins of their time.
Speaking of owls with counterstamps, here one example that is currently on hold at Roma until the shipping situation, due to the pandemic, with RM improves. This coin has some eastern counterstamps, one of which, I believe, definitely includes at least on Egyptian element. That element is the bi-literal hieroglyphic symbol for ss (circled below) in one counterstamp. That symbol can be found in the counterstamp on the obverse. Additionally, on another obverse counterstamp, there is a standing figure to the left, and what seems to be another figure to the right, holding a long object. The outline of the right part of the counterstamp could be that of a vulture (or some avian creature), facing right. I cannot, so far, identify the counterstamp to the lower right. The reverse has a counterstamp that appears to be either a horse or possibly a camel. Here's Roma's information regarding this coin: Attica, Athens AR Tetradrachm. Circa 454-404 BC. Head of Athena right, wearing crested Attic helmet ornamented with three olive leaves above visor and spiral palmette on bowl, round earring with central boss, and pearl necklace; c/m's to cheek / Owl standing to right with head facing, olive sprig and crescent behind, ΑΘΕ before; c/m's in right field; all within incuse square. Kroll 8; Dewing 1591-8; SNG Copenhagen 31. 16.88g, 25mm, 9h. Very Fine. Interesting piece with Eastern countermarks applied.
Mine are later than the Archaics. I got them due to the countermarks: I like the way they attacked Athena, probably marked OUTSIDE the Greek World. By this time, they were making them so fast, that they were just slugs of silver. Athens Owl AR Tet ~17.4g ~20.4mm x ~7.5mm Late Classical 393-300 BC, Sear 2537, SNG Cop. 63 edge-crud
However, I like THESE much more. They are the FRACTIONALS used by the everyday population, in everyday transactions. The Tets were generally used for major purchases between City-States or Major Commerce Transactions. I believe these are much harder to find, as Tets were mass produced and fractionals produced on a much lower scale and were not generally found in hoards. Just a different perspective on the Athenian Owl: Athens Attica 454-404 BCE AR hemidrachm 16mm 2.08g Athena frontal eye - facing Owl wings closed olive branches COP 70 SG 2528 Athens 340-317 BCE AE 12 Athena attic helmet R- Double bodied Owl with head facing E olive sprigs kalathos RARE BMC 224
Yes, and the smaller denominations, relative to the massive output of tetradrachms, are not a readily available, and when they are, they often show considerable wear due to their use in everyday transactions. The profile eye tetradrachms have always seemed to play "second fiddle" to the more popular, earlier archaic eye types of the 5th century BC, and that is often reflected in the lower prices these coins fetch on the market. Well, that's always an opportunity for an astute collectors to acquire some very interesting coins. Also, profile eye tetradrachms can have an appeal of their own, especially when the coin is well struck, centered and produced with well engraved dies.
I think there was initial care in producing these coins, and the quality declined as the necessities of war and capital projects demanded greater output. These coins were trade coins. They were issued by Athens as a means to facilitate trade throughout her empire, and even beyond. As such, traders treated these coins as sliver ingots, stamped with the issuing authority of Athens, guaranteeing their weight and silver content. Of course this did not stop traders and local authorities from marking these coins with their own stamps, as fakes were widespread, and the numerous test cuts seen on many examples testify to a constant need to confirm a coin's integrity. As for stamping or cutting the obverse side, with Athena's profile showing, I imagine most merchants or local authorities wouldn't give it a second thought. Time and expediency were probably more important to most of them than considering whether of not to deface Athens' patron goddess.