About 16 years ago I bought a beautiful Ptolemaic tetradrachm at a coin show in Rochester, NY, pictured below (not slabbed at the time). The coin was attributed to Ptolemy VI Philometor, 180-145 BC, & cost me $400.00. At the time I knew virtually nothing about Greco-Egyptian coinage & sent the coin to David Sear in 2004 for his more detailed certificate of authenticity. The coin came back with a wealth of information & he attributed the coin to the "Aradus Mint (?)" in Phoenicia, with the "date 92 of the Aradian era = 168-167 BC." He graded the coin "good EF, an outstanding example of this scarce and interesting dated series", with no mention of horn silver. About 7 years ago I decided to liquidate most of my Greek coins & focus on Roman coins so I sent this coin to NGC for slabbing & it came back labeled horn silver, much to my surprise . The coin went to a Heritage auction where they made no mention of horn silver in the description & the coin sold for $2,185.00. I never saw anything on the coin that resembled horn silver, neither did David Sear, or David Michaels from Heritage. What do CoinTalk members think, horn silver not ?