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### Isle of Man Decimal Proof (PF) and Diamond Finish (DF) Coins 1978 vs. 1980

This topic mainly talks about Isle of Man proof decimal coins in base metal pre-1980. However, it covers 1981 diamond finish decimal coins. Obviously, it is due to the first £5 (crown-sized) coin in Britain decimalisation system. What is more, a 2017 50p commemorative coin struck at the Tower Mint will be a supportive point to this topic.

What had happened in 1978? It was the year of the 25th Anniversary of Coronation of Queen Elizabeth II. This story is all behind the 1978 proof set. The proof set indicates that the closest relationship between Tynwald and British Monarch. What is more, a 1978 proof set is the very first proof finish standard in base metal in Britain decimal coinage. Back at that time, there was not any proof sets or single coin on the market (e.g., particles, mirror-liked field etc) even the Royal Mint world-class minter had zero product to show, for instance, 1973 50p coin Hands in Hands not struck with a proof finish standard and British decimal set in 1980 onward with a proof finish standard issued.

- 1978 Isle of Man Proof Decimal 8 Coins, mintage unknown

The 1978 proof set contains coins from 1/2d (the smallest value coin) up to Crown, 8-coin with a Pobjoy Mint medallion. The most interesting thing is virenium £1 coin within the set. Also this Pound coin makes a huge achievement in Britain decimalisation history–the very 1st Pound coin, considering Great Britain Pound coin issued in 1983. The 1978 proof set issue limit is **unknown**, this is very typically and mysteriously things they love to do. I personally would say it is 1,000 sets (or less, this would be dependent on the demand variable and the proof set popularity variable in 1978). Why is 1,000 sets? Please see 1981 Diamond Finish decimal 8-coin with £5 and 1972-74 decimal 6-coin, they are all 1,000 sets each.

It is said that they (the Pobjoy mint) upgraded their machinery in 1980 and declared Diamond Finish (DF) Standard for a higher standard finish to collector at same year. Actually, DF is highly likely a prooflike finish (see 2017 the Treasure of Isle of Man, “press once on pre-polished blank”), lower than proof finish standard in terms of grade. See supportive evidence that 2017 Isle of Man House of keys 50p proof coin. Tynwald did not allow their new staff IOM post office (used to be the Pobjoy mint job) sell and advertise 50p “proof” coin instead a letter from the Treasure cancelling wording “proof”, but coins were actually struck at a proof standard by their new minter the Tower mint. Here it is another story untold.

Next, it is 1980 diamond decimal set.

- 1980 Isle of Man Diamond Decimal 7 Coins, limited at 25,000 sets

You probably notice that coin grade between 1978 and 1980 is totally different. This is the significant difference between the two decimal sets in terms of coin finish standard. It is probably the reason they declared the diamond finish in 1980. The 1978 decimal set coin was struck at level of proof finish standard, however the 1980 set coin was only a diamond finish standard (i.e., prooflike finish). Also, the 1980 set had no crown sized coin with it. This might be a clue directing that a new higher nominal face value coin would be born in 1981? The DD batch code/die mark was shown on the 50p CN coin and BB on £1 coin in 1980. The prefix B and prefix D assigned on decimal diamond finish sets have had a stir internally, but finally the prefix B was the winner (please see IOM Xmas 50p diamond finish BC coin (1980/1981) and/or Gibraltar Xmas 50p DA coin (2019)). As you can see above, the 1978 50p proof coin has no die mark on (ND). Later soon, a 50p coin of a 1984 Decimal diamond finish set is ND as well. However, the first Xmas 50p coin with ND was struck in 1994 Wren hunt. At this moment, it has no any evidence indicating the relationship between a 50p proof coin w/ ND and a 50p proolike coin w/ ND. But array of the years, 1984 & 1994 and 1987 & 1997, are another things to look into.

Finally, 1981 diamond decimal set comes to an end of this topic.

- 1981 Isle of Man Diamond Decimal 8 Coins, limited at 1,000 sets

The year 1981, it had two different decimal sets, 7 coins without £5 crown-sized coin limited at 25,000 sets and 8 coins with £5 crown-sized coin limited at 1,000 sets. Eventually, it had a total of 26,000 sets. Oooohh, wait, 1,000 sets for 8-coin set, the no. 1,000 echoes a). 1,000 sets of 1972/73/74 decimal UNC 6-coin respectively and b). 1000 years of Tynwald 1979, the oldest continuous parliament in the world. Therefore, it concludes that the mintage of 1978 decimal proof set it was highly likely to set at 1,000. How many sets sold in the past, nobody knew.

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