@Spaniard PM you about the existence of a coin he thinks you'd be interested in. Step 2: Look at the seller's photo and say to yourself, "I've never seen anything like that!" Step 3: Have a healthy skepticism about the seller/previous collector's attribution, which attributes it to the city of Poroselene in Aeolis. Step 4: Investigate possible matches to coins in Poroselene and find one with a youth riding dolphin reverse, RPC IV.2 10103, but notice that the dolphin is swimming right and the style is very different. Moreover, the reverse inscription on that coin reads ΠΟΡΟϹƐΛΗΝƐΙΤΩΝ, which is incompatible with the few letters on the reverse of the unknown coin. Search for "Poroselene" at RPC to see if the reverse appeared on other coins of this city, but notice there are no others. Step 5: Recognize that the inscription is probably in Latin and not Greek. Post what you know about the coin and ask other members of CT for help. Step 6: Get help from @zumbly , who recognizes that the reverse possibly reads [C] I C A for Colonia Iulia Concordia Apamea. He notes that RPC Online doesn't yield anything for Faustina with a dolphin from that city, but found a similar coin of Commodus with Venus seated on a dolphin: https://rpc.ashmus.ox.ac.uk/coins/4/4735 Step 7: Search the listing of Antonine coins of Apamea in BMC 13, pp. 112-13. While the British Museum collection has nothing with a dolphin, you note the inscriptions read C I C A D D. You notice that the two duplicated letters below the dolphin's head (that look like d d or p p, depending on if they are upside down or not) and may well be D D (for Decurionum Decreto, meaning by decree of the decuriones, the local councillors of the municipality). Step 8: You note another coin from Apamea of Geta with a similar reverse when you do a search at acsearchinfo: Step 9: Now that you're pretty sure the coin is from Apamea in Bithynia-Pontus, search RPC and find four coins of Faustina from Apamea in RPC IV, and notice the existence of one (RPC IV.1 4729) where the authors note that the V in Faustina as well as in the reverse legend are rendered as a U. You suspect that the coin is an obverse die match to the coin in question, even though the reverse features Neptune. Step 10: You note that RPC cites cites Waddington, Recueil Général 55, p. XXXIX.1, which is available online. Here's the plate coin: Step 11: Note two things: a) the DD on the reverse of that coin has CICA DD rendered as CICA dd, just as on the coin in question, and b) doing a little photo processing, rotating the obverse and putting it side-by-side with the coin in question yields -- BINGO! A die-match! Step 12: Now that you've identified the coin with certainty as coming from Apameia, you can reconstruct the obverse legend exactly and, failing to find other examples in RPC (which is very comprehensive, citing almost all the museum collections and references of importance), on acsearchinfo, wildwinds or other databases, you conclude it's unpublished and attempt to reconstruct the reverse legend and describe the devices on the reverse, which are not entirely clear on the coin in question. You find other coins from Apamea with a similar reverse type in Mionnet Supplement 5, of all places, and compare. You compare the legend on the companion coin with the Neptune reverse from Waddington's RG and cited in RPC. Step 13: You photograph your coin and write up your findings for the world. Faustina II, AD 147-175. Roman provincial Æ 5.84 g, 22.0 mm, 7 h. Bithynia-Pontus, Apamea. Obv: FAUST[INAC AUG], draped bust of Faustina II, right. Rev: UЄNU[S ... C]ICA dd, Venus seated right, head left, on dolphin swimming left, resting right arm on dolphin, uncertain object in left hand. Refs: RPC --; Waddington RG --; BMC --; Sear --; Mionnet Suppl 5 --; Lindgren --; Wiczay --. Notes: Apparently unpublished. Obverse die match to RPC IV.1 4729.