Often I see coins listed that say "reverse of" on the slab. For example a 1990 penny with a reverse of 1989. I don't get it, the reverse of one year and the next should be the same, aren't the dies always matched? ...and how can the reverse be from a different year, if the design is the same?
This is a case of minor differences in the design from one year to the next. Probably the best example I can give is with the 1878 morgan which had 3 reverses, 8 tail feather, 7/8 tail feather (restrike over the 8) and 79 reverse (7 tail feathers without a restrike). I have also in my recent reading about US large cents that this occured as well for several different dates where minor changes were made then reused the next year as well so the previous year coins are listed/described as having the reverse of the next year.
It's what they call a transitional year for some of the engravings. For example, the FG initials for the reverse of the 88 cent has a transitional variety. Which makes this dated transitional a very sought after example. Other examples of transitional are newly designed reverses, type style changes and so on. Some very subtle like initials to very easy to see devices.
No, they are not. Easy, it is because every year new dies are made. And the dies made this year, can be slightly different (have different die diagnostics) than those dies made the previous year. But, if and when dies from the previous year go unused, or they still have life left in them, then the mint will use those old dies. That results in a coin, to use your example, with a reverse of '89 (dies left over from '89) and an obv of '90 (dies from '90).
Another more recent example would be the 2008-W SAE with the '07 Reverse. If Detecto would just take the time to do a little more reading............ Chris
Transitional varieties occur when an obverse or reverse die is matched with its counterpart, but has the design variety of a previous year, or sometimes with the design of the next year, or a design not meant for circulation. I can think of a few right off the bat on lincoln cents: -1988P and 1988D with the reverse design of 1989-minted cents, the "RDV-006". -1992P and 1992D "Close AM" cents, which are rare, were minted with the reverse design that was intended to start in 1993. -1998-2000P "Wide AM" cents were made with the reverse design of a proof die. -1998S and 2000S Proof cents with a "Close AM", made with the reverse of a die intended to mint business strikes.
I'm inclined to agree. But then not everybody knows where to look, or even how to look, to do that homework. Some of them just need pointed in the right direction. Some will need more help than that. And some will need no help at all. Unfortunately, the latter tend to be few.