The silver tetradrachms of Athens, which pair the helmeted head of the goddess Athena with the standing figure of her owl, were produced on a very large scale from the mid- to late-5th Century B.C. 
One design element on these coins that almost always is missing or is incomplete is the horse hair crest that adorns Athena’s helmet. The broadness of the obverse dies and the comparative narrowness of the planchets assured that most every Athenian tetradrachm of the Classical period was missing at least half of its crest.
Usually when a ‘full crest’ owl is found, it’s at the expense of Athena’s chin and/or nose since the completeness of the crest is gained only by the loss of design elements at the opposite end of the obverse die.
Thus, to find a full crest owl on which Athena’s chin and/or nose also are present is a very rare circumstance. And even when that small miracle occurs, one can only cross their fingers that the surface is pleasant – with sound metal and none of the distracting defects, such as test cuts, graffiti, countermarks, scratches, scuffs and improper cleaning, which so often mar these coins.
This is an unbelievable example we just got back from grading at NGC Ancients. The design struck on a large uniquely shaped silver flan. Our coin achieved the FULL CREST designation. It is thought that less than 1% of all Attica Owl Tetradrachms will get this designation, a rarity among rarities.