GOOD LUCK! Byzantine gold coins are some of THE most difficult coins to authenticate. I would seriously question the abilities of ICG or even NGC to work with these. The only thing you can really do (even though it is cliche) is to buy from reputable dealers. Try the voluminous Ancients section of vcoins.
Thanks. So far I am buying from Austin rare coins and Ancient Imports, but in a very small way. I trust Austin for new gold.
I would agree with Vcoins as a good and trusted source. Another would be CNG, you won't go wrong there. I'm not sure that NGC even slabs Byzantine coinage, they might. If they do, I would certainly trust their authenticator Ken Krah. I would also trust ICG for authentic coins. As Ardatirion ha spointed out in the past, they may miss the attribution, but I wouldn't worry about buying a counterfeit in their slabs. Also, if you are truly interested in this coinage then I suggest you get a couple of books to start with. First would be Gold Coins of the World by Friedberg 7th edition. After that, look for books on the subject by Phillip Grierson, one of the recognized authorities on the subject.
Try Vcoins, go here: http://www.vcoins.com/search/ and do a search for 'Byzantine' or if you are looking for something specific...That will search all the sellers on Vcoins. All sellers on Vcoins follow a strict code of ethics which means most have a lifetime assurance that it is real or money back. Each VCoins dealer pledges the following: I will not knowingly deal in counterfeits, copies, or reproductions without full and clear description of their nature. I will never knowingly represent such items as genuine. I will not knowingly deal in stolen numismatic items. I will report such items to the proper authorities if they are offered to me. I will vouch for the authenticity of items I sell and will have no time limit on the return of items discovered to be non-authentic. I will offer a full cash refund upon return of any such item, including the cost of return shipping. I will explicitly state my terms and conditions of sale in my e-store. I will not intentionally misrepresent items I sell, including the use of misleading images, historical conjecture, unsubstantiated provenance or pedigree, or other tactics that may artificially inflate the perceived value of an item. I will operate in a fair and honorable manner, and will not intentionally defame the character of my competitors or the quality of their products. and many have been around for a long time, they will not ruin reputations and business by selling a fake or not making good if it is found to be fake. if you want to authenticate the coin, your best bet for ancients IMO is David Sears but there are others as well: http://www.davidrsear.com/certification.html Also his book would be the best and most thorough on the subject I would think, not cheap but then neither are gold byzantine coins : http://www.davidrsear.com/byzantine_coins.html
I generally only trust VCoins dealers (there are a few others) for stuff like this, their code of ethics means they guarantee authenticity & they have enforced it in the past. Note many VCoins dealers (HJB, CNG, Ancient Imports, etc.) also have their own websites separate from VCoins & sometimes they have more stock on those sites, so check for both.
