Interesting Topic Kipsley. I have spent a
lot of time researching this subject and it is complicated. Regardless of what the above posters have said about Mintmarks & Privymarks the meaning of them is very different on Australian decimal coins, especially the Australian dollar in recent years. The Australian Dollar Coin in various forms/editions has had 189 Mintmarks, Privymarks & Counterstamps applied to them up to the end of 2018.
The first one which had raised Letters C, M & S was the 1993 "Landcare" dollar which had a "C" (Canberra), "M" (Melbourne) & "S" (Sydney)
Mintmark applied to it. >>
https://en.numista.com/catalogue/pieces7358.html
These Mintmarks were applied to the coins in the Cities indicated, at the Public Gallery Press in the Royal Australian Mint in Canberra, and on the Mobile Presses at the Royal Melbourne Show and the Sydney Easter Show. So they are true
Mintmarks. This basic premise was followed on all the Mintmarked coins issued by the RAM whether at the RAM or on the Mobile Presses until the Year 2000 on the "HMAS Sydney" Dollar. >>
https://en.numista.com/catalogue/pieces12610.html
Then in 2002 on the "Year of the Outback" dollar coin only the Canberra coin had a raised letter "C" Mintmark, the Brisbane, Melbourne & Sydney coins had a raised letter in an incused circle. The RAM, at the time, still called these Mintmarks but we now call these types of marks,
Counterstamps (B), (M) & (S) respectively. >>
https://en.numista.com/catalogue/pieces6897.html
There then came a period of what the RAM at the time still continued to call them as Mintmarks, but were actually what we would now call them as Counterstamps. That is they were all raised letters in an incused circle. The first coin this applied to was the 2003 "50th Anniversary of the Korean War" dollar which had (C), (B), (M) & (S) Mintmarks/Counterstamps. >>
https://en.numista.com/catalogue/pieces19372.html
This pattern was followed until 2007 on the "75th Anniversary of the Sydney Harbour Bridge" dollar, that is raised letters in an incused circle. Some of the coins in this period were struck in the individual Cities on the Mobile Press and some were struck at the RAM and sold by dealers nationwide. That is the (B), (M) & (S) Counterstamps were also struck by the RAM in Canberra. >>
https://en.numista.com/catalogue/pieces13907.html
Then in 2008 when the "100 Year Anniversary of the Australian Coat of Arms" coin was released the RAM made quite a big change. This was the first year they released a four coin set which went back to the "C" coin being a Mintmark (Raised letter C) but the other three had an incused letter in a small raised Square [B}, [M], [S] etc. They also started to call these marks as
Privymarks.
They also continued to stamp coins in the individual Cities, Brisbane, Melbourne & Sydney with (B), (M) & (S) Counterstamps, that is a raised letter in an incused circle. And they also stamped out coins on the Gallery Press at the RAM in Canberra. So there were 8 different versions of the same coin, although it was difficult to tell the difference between the "C" Gallery press coin and the "C" coin included in the four coin set. Experienced collectors could tell them apart by small differences in the location of the mark or its depth/strength >>
https://en.numista.com/catalogue/pieces13908.html
This new pattern of "C" Mintmark & [B} [M] [S] etc Privymarks in the 4 coin set and (B), (M) & (S) Counterstamps sold in the actual Cities, but not necessarily stamped in those cities, has continued to date.
The RAM for a little while also expanded the 4 Coin sets to include Privymarks from Adelaide, Darwin, Hobart & Perth [A], [D], [H] & [P] for a while but they only did that for a couple of years. They also occasionally put out a coin with a unique one off Counterstamp such as (TV), on the "50 Years of TV Coin" or (E), on the "Eureka Stockade" coin, or (G) on the "90 Years Since Gallipoli" coin. The very latest one is the 2018 "100 Years of Anzac" coin that has been Counterstamped at the RAM Popup Shop at Albany with an (AL) stamp. Only 5000 of these were made.
These Mintmarked, Privymarked & Counterstamped dollar coins are considered within the Australian coin collecting community as different releases. This is why I have put a lot of work into putting them all on Numista as separate entries and describing them with their individual marks/stamps and Mintages etc.
(There are also 2 coins with Edgemarks)
Some have very low mintages and command high prices due to being very hard to obtain.
The 2013 "Bi-Centenary of the Holey Dollar" (B) Counterstamp has the lowest Mintage at 2,403.
To summarise then ..... by my reckoning there are up to the end of 2018 ......
47 $1 Coins with Mintmarks > "C"x21, "M"x7, "S"x9, "B"x5, "A"x4, & 1 Master Mintmark coin.
75 $1 Coins with Counterstamps > (C )x8, (A)x1, (M)x18, (S)x17, (B)x15, (P)x4, (E)x1, (G)x1, (GC)x1, (TV)x1, (AL)x2, (Map)x5 & (Bluebell)x1
65 $1 Coins with Privymarks > [M]x15, [S]x15, x14, [A]x2, [D]x2, [H]x2, [P]x7, [WMF]x4, [PA}x1 & the recent [A]x1 [U}x1 [S]x1 Dollar Discovery ones
2 $1 Coins with Edge Marks > 'C'x1, 'S'x1
"Mintmarks" are a raised letter only on the field of the coin.
(Counterstamps) are a raised letter or symbol in an incused Circle.
[Privymarks] are a letter or symbol (Such as the Ampelmamn one) incused in a raised Square.
'Edge Marks' are pretty self explanatory.
Cheers Mike
Master Referee - See my profile for what I collect.