Since the advent of eBay , fake cobs have proliferated online.  Since many counterfeits look perfectly good in photos, you don't know you are bidding on or even buying a fake till you actually receive it.  Often the weight will tip you off, but sometimes not.  For years now I have been "policing" eBay  and helping clients avoid these fakes, and I will continue to advise anyone who asks.  Below are some that are not readily detectable as fakes from the photos, but are known to be fakes simply by virtue of the fact that several different specimens exist with the exact same details and shape (never a reality on authentic cobs). Click here to check our FAKE COB DATABASE

ID#	"Fake Cob type"	Photo (Click to Enlarge)	Comments
#FC43601	Mexico, 3 reales, Carlos-Juana, "Early Series"		Many have been seen lately different patina and shape for the flan, even one gilt. 8.1 grams.
#FC43602	Mexico, 4 reales, Carlos-Juana, "Late Series," M to left, L to right (post-1554 type)		Note I actually sold a specimen of this fake in 2005, and as recently as July, 2006, it was being offered by Chinese seller cliff* on eBay .
#FC53624	Mexico, 2 reales, Carlos-Juana, "Late Series," M to left, G to left (post-1554 type)		Very common, hard to spot, many finishes different weight but around 6.8 and 6.1 grams.
#FC53625	Colombia, 2 Escudos - Mid-1600's. possibly gold-plated in some cases		Another gold-cob fake that is turning up a lot in South and Central American markets is this mid-1600s 2 escudos made out of base metal or silver
#FC53626	Mexico, 8 reales, 1630D		poor cast, commonly seen on eBay.
#FC53627	Mexico, 8 reales, 1635P		Note this is identical, except for the date, to 1647/6P and 1657P #3 below, and this same planchet exists with contrived full dates 1634, 1637, 1649, 1655, 1656, and 1667
#FC53628	Mexico, 8 reales, 1647/6P		Note this is identical, except for the date, to 1635P above and 1657P #3 below, and this same planchet exists with contrived full dates 1634, 1637, 1649, 1655, 1656, and 1667
#FC53629	Mexico, 8 reales, 1652/42P		(piece shown here was originally offered from an eBay seller from Asia) Other sellers from other parts of the World might be offering the same piece as well.
#FC53630	Mexico, 8 reales, 1653P #1		(piece shown here was originally offered from an eBay seller from Asia) Other sellers from other parts of the World might be offering the same piece as well.
#FC53631	Mexico, 8 reales, 1653P #2		(piece shown here was originally offered from an eBay seller from Asia) Other sellers from other parts of the World might be offering the same piece as well.
#FC53632	Mexico, 8 reales, 1657P #1		(piece shown here was originally offered from an eBay seller from Asia) Other sellers from other parts of the World might be offering the same piece as well.
#FC53633	Mexico, 8 reales, 1657P #2		(piece shown here was originally offered from an eBay seller from Asia) Other sellers from other parts of the World might be offering the same piece as well.
#FC53634	Mexico, 8 reales, 1657P #3		Note this is identical, except for the date, to 1635P and 1647/6P above, and this same planchet exists with contrived full dates 1634, 1637, 1649, 1655, 1656, and 1667
#FC53635	Mexico, Royal 8 reales, 1646P		This one has been offered several times by the same eBay  seller, keywestdivers.  it appears this coin was cast from Lázaro's specimen.  In any case, the usual red flags are there (private auction, no returns), so no one should be bidding on it anyway, but so far the bids are in the thousands of dollars--well into the range in which someone must think it is genuine. *
#FC53636-A	Mexico, 8 reales, Early-1600's		Another Mexican cob 8R fake, this one actually fooled me till I saw it in person and noticed telltale tiny balls on the surface, otherwise (and especially from just a photo) it passes very easily for a nice "Rill Cove wreck" (ca. 1618) specimen with the edges corroded away
#FC53636-B	Mexico City, Mexico, cob 8 reales, Philip II, assayer F.		Another Mexican cob 8R fake.24.62 grams. This fake have been
#FC53636	Mexico, 8 reales, oMF Phillip III		Another Mexican cob 8R fake. 24.8 grams. Metal is usually silver and the patina looks authentic.
#FC53637	Mexico, 8 reales ROYAL, 1610F		Another Mexican cob 8R fake.
#FC53638	Mexico, 8 reales, 1714J (Fleet)		Supposed to be from the 1715 Fleet (corroded, underweight, etc.) but I have seen at least two identical specimens
#FC53638-AB	Mexico, 8 reales various "fleet" cast copies in lucite block.		Supposed to be some sort of promotional done with a gift shop in South Florida, all the pieces here shown are cast fakes.
#FC53639-A	Mexico, 8 reales, framed fleet coin		4 reales, Philip V, assayer not visible, framed. The other side pasted to its original certificate. With FAKE Cobb Coin Co. certificate #154127. (auctioned by us back in 2012. (transaction withdrawn/cancelled) Many fakes framed and glued casts still are being offered on eBay, be very careful.
#FC53639	Mexico, 8 reales, 1715J (Fleet)		Another one supposed to be from the 1715 Fleet, and seems to be a pretty good fake till you see its litter-mates (and they always seem to be mounted...)  As a further note on this one, seller 2006edgec sold this coin as genuine even though he had been told (and shown) that it was fake, so you might want to avoid his offerings in the future. Other coins has been offered as "Treasure coins" all fakes as well.
#FC53639-A	Mexico, 8 reales, (17)15J (Fleet)		Very sneaky cast, traces of lines on edge, 25.8 grams paired even with genuine cert, we have seen it only once.
#FC53640	Mexico, 8 reales, (1710-15) (Fleet)		The only way to tell is because we had two coins alike in our hands.
#FC53641	Mexico, 8 reales klippe, 1733MF		Note:  this is a highly counterfeited type, but this particular fake is cropping up a lot these days and is identifiable by the four "plugged holes" in the corners, which are rendered simply as flat spots in the casting. Other type of 1733 fakes are also being offered on eBay ,(rectangular shape)
#FC53642	Mexico, 8 reales klippe, 1734MF		Another klippe but this one dated 1734.
#FC53642-A	Mexico, 8 reales klippe, 1734MF		Another klippe but good "fabric" with countermark and hole in different places, fooled some auction houses, probably seen 3-4 times.
#FC53643-B	Mexico, 4 escudos, 1711 Royal		There is also a proliferation of fake Mexican gold cobs touted as being from the 1715 fleet, 5 grams.
#FC53644	Mexico, 2 escudos, 1713		There is also a proliferation of fake Mexican gold cobs touted as being from the 1715 fleet.
#FC53645	Mexico, 8 escudos, (1714-1715)		There is also a proliferation of fake Mexican gold cobs touted as being from the 1715 fleet.  20 grams.
#FC53645-B	Mexico, 8 escudos, 1714J		There is also a proliferation of fake Mexican gold cobs touted as being from the 1715 fleet.
#FC53645-C	Mexico, Gold Cob 1715 Fleet Set		reproduction made in 22k gold.
#FC53646	Mexico, Gold Cob 1715 Fleet Set		There is also a proliferation of fake Mexican gold cobs touted as being from the 1715 fleet.  I have seen them offered individually, but here are some group shots (an 8-4-2-1 denomination set) from seller hobie1965, who refused to withdraw the sale even after being shown identical coins in other auctions
#FC53646-A	Mexico, 8 escudos, oMF 1731		An old well known fake.
#FC53646-AB	Mexico, 8 escudos, oMF 1731		An old well known fake, 23,3 grams.
#FC53646-B	Mexico, 4 escudos, oMF 1731		An old well known fake, 13,3 grams.
#FC53646-C	Mexico, 2 escudos, oMF 1731		An old well known fake, 3,3 grams.
#FC53647	Potosí, Bolivia, 8 reales Royal, 1707Y		Over the past several years I have seen a particular brand of counterfeit coming out of Peru that is more fanciful than deceitful, as the designs are not like the genuine coins. This is a good example and following many more...
#FC53648	Potosí, Bolivia, 2 reales, "Philip II, 1593"
#FC53649	Potosí, Bolivia, 1 real Royal, 1686VR		Also seen with the shape of a heart.
#FC53650	Potosí, Bolivia, 8 reales, Philip IV, P-T		This cob and the following two, on the other hand, are more dangerous (at least when buying from a photo) because they are cast from genuine examples
#FC53651	Potosí, Bolivia, 4 reales, Philip II, P-B
#FC53652	Potosí, Bolivia, 1 real, Philip II, P-M
#FC53653	Potosí, Bolivia, 8 reales, 1652E transitional Type III		Some other Potosí fakes to watch for are copies made from some pieces recovered from a wreck that sunk in the 1650s.
#FC53654	Potosí, Bolivia, 8 reales, 1653E		Note:  this particular piece comes from a seller in China)
#FC53655	Potosí, Bolivia, 8 reales, 1653E #2		Note:  this one comes from eBay  seller "komakoma", whom many of my customers have asked me to watch, yet this is the first specimen of his that I have actually examined in person to be able to condemn it
#FC53656	Potosí, Bolivia, 8 reales, 1653E #3		Note:  this one is an "official replica" made in Ecuador to commemorate the Capitana salvage
#FC53657	Potosí, Bolivia, 8 reales, 1654E "Capitana"		Apparently that was not the only "casted" cob from the Capitana salvage, there are a few more examples around, including countermarked "L" pieces.
#FC53658	Potosí, Bolivia, 8 reales, 1651/2E "Capitana"
#FC53659	Potosí, Bolivia, 8 reales, 1655E		Note:  another "komakoma" offering that is likely to crop up again
#FC53660	Potosí, Bolivia, 8 reales ROYAL, 1676E		Sold at least twice by eBay  seller "nammibob" despite notification. (Note we lack of scan for the reverse)
#FC53661	Potosí, Bolivia, 8 reales, 1687 with countermark from Guatemala.		very common cast.
#FC53662-B	Potosí, Bolivia, 8 reales, 1688VR		very well done cast probably in many collections. Weight is usually approx 26.55 grams
#FC53662	Potosí, Bolivia, 8 reales, 1692VR		very common cast.
#FC53663	Potosí, Bolivia, 8 reales, 1696VR		A classic! In addition, here is a fake that should be recognizable as such by anyone but a neophyte, yet it crops up as genuine on eBay  all the time (most recently [September, 2006] by seller "vintage_comics_and_collectibles"
#FC53664	Potosí, Bolivia, 8 reales, 1696VR		And a similar one, recently offered by "paulelaine2524," who had some other fake cobs for sale as well and refused to remove them.   (Note:  This seller now goes by the name of "pgar299422" on eBay .)
#FC53665	Potosí, Bolivia, 8 reales ROYAL, 1704Y		Very dangerous fake using impact dies. At least 2 seen.
#FC53666	Potosí, Bolivia, 8 reales, 1730		A very common cast fake that has been around for decades and is now cropping up on eBay
#FC53667	Potosí, Bolivia, 8 reales ROYAL, 1734E		Note that this appears to be cast from a genuine coin that was offered on eBay  in late 2005, but I know that that coin was genuine because I examined it in person
#FC53668	Potosí, Bolivia, 8 reales HEART, 1742C		Note that the too-neat style of this coin typifies the fantasy pieces coming out of Peru in recent years
#FC53669	Potosí, Bolivia, 8 reales, 1760q		A very common cast fake that has been around for decades and is now cropping up on eBay
#FC53670	Potosí, Bolivia, 2 reales HEART, 1786		A very common cast fake that has been around for decades and is now cropping up on eBay
#FC53671	Santa Fe, Colombia, 8 Reales, 1652		In 2005 the Perth Mint produced a 13 piece collection of replicas, including the coin illustrated here. This is an "official" reproduction. The Perth Mint is wholly owned by the government of Western Australia and is operated by Gold Corporation which was created under an Act of Parliament
#FC53672	Lima, Peru, 8 Reales, 1684		You will find this coin everywhere, even in some coin shows, being offered as a "fleet" cob.
#FC53673	Lima, Peru, 8 reales, 1700H		Yet another Chinese fake, this one for Lima!
#FC53674-A	Lima, Peru, 8 Reales assayer Rincon		This is fantasy very well done with the right weight, bought at a market in Peru.
#FC53674	Lima, Peru, 2 escudos 1705		This is a replica plated, made back in the late 70's, early 80's. (about half the real weight)
#FC53675-A	Lima, Peru, 4 escudos 1710		We have seen this mounted, wellmade high karat gold used. We have seen it 3-4 times. Always underweight.
#FC53675	Lima, Peru, 8 escudos 1711		This is a replica plated, made back in the late 70's, early 80's. (about half the real weight)
#FC53676	Lima, Peru, 8 escudos 1712		This is a replica plated, made back in the late 70's, early 80's.
#FC53677	Lima, Peru, 8 escudos 1712		This is a replica plated, made back in the late 70's, early 80's.
#FC53678	Lima, Peru, 8 escudos 1714		This is a replica made in gold.
#FC53679	Lima, Peru, 8 escudos, 1736N		This one was sold by seller "estatedoctor" along with many other bad cobs ("private auction"--usually a red flag!) even after I notified him that they were fake.  Note also that several cast fakes of this date are known, including some copies marketed by Disney World at their Pirates of the Caribbean gift shop

One last footnote:  This page applies only to cobs, but internet buyers should be aware that there is a huge rash of fake pillar dollars (and minors) many being offered from Asia, not exclusively but in more quantities than other places, (NOTE: the fact that a piece is being sold from this part of the word DO NOT automatically implies the piece is not good, however; many sellers, unfortunately, tracked to that area offer counterfeit pieces.) In recent years we have seen fake pieces being offered from Europe and Middle East as well as some part of South America and North America.  Be VERY careful buying from anybody in that part of the world (IN GENERAL), and be especially sure to avoid any private auctions (where bidders cannot be warned by the experts) no matter from which part of the world you buy the coin from just be sure you know you are dealing with a serious and professional seller that knows the material and/or will honor any returns as well.