As you might suspect I do own examples of all 4 coins show in the 4 auctions and I will describe them now.
Example 1 is a cast copy of a genuine Hookmeck coin from Mexico from 1823 - the edge is rolled on after the coin was cast and the edge was ground smooth to remove the casting seam. The metal is not silver but it approximates a form of German Silver is non magnetic rings but incorrectly has a specific gravity near 9.9. My copy is underweight. Details are crude due to the way the molds were created with a grainy matrix. The coin dates from the 1950s and I believe it was produced in Mexico (based on discussions I have had with Dave O'Harrow. The same type is illustrated on page 215 of "Hooknecks". It is a class 3 coin a Numismatic Forgery. The seller is aware of what the coin is and in my opinion has provided a rather clear warning to anyone who reads his description.
This auction could be made acceptable (in my opinion) if
ebay allowed the seller to indicate specifically what the item is. There is no need to stamp the item COPY it predates the HPA. This auction and coin are VERY low on the threat scale.
The second coin is an 1842 Zs OM which uses the same eagle die as the Riddell # 237 which used a Cap Die dated 1834 Zs OM. Since Riddell's book was published in 1845 the coin is a Class 1 Contemporary Circulating Counterfeit. The coin is a struck variety. In my collection I have over 3 dozen examples of this same die in two distinct varieties (the scarcer second variety uses a heavily recut die which added or strengthened many elements. Metal varies widely from 70% silver to 0% silver. There are plain copper, Sheffield plate and German silver examples. The coin is collectable and slightly scarcer than the 1834 Riddell version. This auction as presented is a FRAUD. The coin is totally misrepresented and over graded. That said idiots such as my self do collect this type of fraud to prove they exist. The value of the coin not encapsulated is likely $30 or less. The outfit that encapsulated the coin is the same one that sued
ebay for discrimination so termination by
ebay is unlikely. The coin does not need to be marked COPY but the holder should correctly identify it. The danger here is the encapsulation as noted earlier. It is a very dangerous Class 1 presented in a fraudulent way.
The third coin 1884 Zs IS is a very recently produced numismatic forgery a Chinese product that is struck from machine engraved dies. The engraving dots are visible on the coin when you see it at high resolution. It is the most recent of the 4 and should bear the word COPY as production after 1974 is well documented. The metal used was at one time pure nickel and magnetic. More recently the planchets are copper-nickel and no longer magnetic. This is the current variety of this same date 1884 Zs JS which has been produced since 1940s. The s superscript on the mint mark is a dollar sign $ not an S and the assayer's initials have been altered to IS because the people in charge do not know what the straight J font looks like. Early strikes were 20 grams because the makers also had no clue about the assay definition which ends 20 Gs (standing for 20 grannos). It does not mean 20 grams is the correct weight. More recent examples are heavier with thickened planchets. Normally the edges are reeded using a ring die but a few very recent examples approximate a correct edge. The design is so corrupt that it should not be a problem - but it always sells for some reason. It is dangerous because as presented the auction is a fraud and these bad fakes always get bids. It could simply be that some novice collectors believe all counterfeits are valuable - they do not distinguish between counterfeits and numismatic forgeries which this coin is. It is a Class 3 coin and extremely dangerous because at the end of the day this coin is WORTHLESS - unlike the encapsulated Class 1 coin which still is of some value.
The 1833 D RM is a very odd coin. It is part of a much larger family of counterfeits which involve numerous cap and eagle dies which are involved in every conceivable combination. I refer to the bird here as a Ca/Go bird because of the family resemblance. This is a common to very common counterfeit that is tentatively placed in Class 1 but which may be a VERY early form of Class 3. It apparently did circulate in the 1800s based on exemplars discovered with early cancellations and heavy wear. There is no ABSOLUTELY CONCLUSIVE proof of age however. The coins are debased silver of varying qualities and they are struck. The dies are likely hubbed but more exemplars need to be studied along side each other for sequencing of damage. The edge designs are applied with a two bar edger but the priority varies and there are more than one die pair in use. The coin has several significant errors that point to a more modern origin. The mint mark is a D with no superscript. The assayer initials which are correct for Durango contact the date. The rays are carved outlines not punched elements with centers that rise above the fields. The lettering on the Cap is raised not incuse. The 0 in 10 and the 2 in 20 are doubled. The eagle is a cross between the Chihuahua bird and the Guanajuato bird but a bit thinner with an open mouth. The details of all three leaf types are poorly done. The coin is test cut and well toned.
So my answers are 1- Class 3, 2- Class 1, 3 Class 3 and 4 Class 1 or 3.
Danger to a novice bidder is highest in the case of #3 unless they check the design and lowest in the case of #1. The other 2 coins are in my opinion on a par - both are fraudulently listed because of either
ebay rules or seller ignorance or greed. The second coin the encapsulated copy may draw higher bids but will also likely in the end be worth MORE - a push.