Colour as a Key to Coin Grading
Intro
One of the most useful pointers I’ve read from PCGS’s extensive writings is that a grader needs to handle fake and impaired coins on an almost continuous basis to better understand the degrees of BS that are out there. However, PCGS has muddied the waters on the various grades I’ve received from coins submitted and coins that I have purchased. Their grading suggests opinion or varied understanding of Australian bronze pre-decimal coinage. It is for this reason that I have made colour one of the key focuses in better understanding Australia’s numismatic history.
The Industry Shonkies Continue
Auction houses are not your friend. They exist to move as much product as they can to ensure their commission. How they display their product is what defines their integrity. The above 1939 Half Penny is a recent acquisition from an auction house. The description was amusing; something along the lines of “previously cleaned but amazing colour – an ideal candidate for a collection”. Normal light photography (right side) shows a yellow brown coin whose colour is questionable, but not necessarily a deal breaker (if the price was right). On the left is the coin seen with axial photography. The colours and pattern of toning clearly denote issues. However, the reality is worse as both photographs were compensating for the excessive brilliance of the toning left by cleaning. This coin is shiny gold & purple in the hand – a real shocker. It has been blatantly cleaned and would not feature in any auction that Top End Coins will hold in future. It was purchased to further reinforce and illustrate the difference between artificial colour through interference and natural colour.
PCGS Questionable Colour
The above coin is PCGS UNC Questionable colour and the certificate can be viewed here. This example and a sister coin from 1916 (which can be viewed here) was what got me started in the research on colour. This coin has this particular colour because it is Phosphor Bronze. A quick Google search for phosphor bronze brings up images like the following:
Well what do you know! Phosphor bronze really does look like that colour. So why aren’t all 1916 Bombay pennies looking like the above example? Oxidation plays a role in dulling colour and it is likely that the collector of the above example took measures to ensure that oxidation would be impeded. I cannot tell you what measures were taken. Each age of collecting have their bag of tricks for preserving and enhancing a coin. In a country that is today content to use Brasso and WD40 to treat coins, it’s impossible to determine what measures were taken to preserve the above coin 100 years ago. I know of no chemical that can strip away patina without irreversibly damaging the metal surface and that coin’s surface is not damaged.
PCGS Cleaned?
I send coins to PCGS to determine what opinion they will form on the coin. The above example is the most recent to be sent. It is again 1916 and is showing the natural toning written by Doug Kurz for his legendary Morgan dollar collection sold in 2009. By clicking on this link you can see that this coin has thin film progression extending from approximately orange through magenta blue (K thru N). The obverse fields show signs of wiping, however it may just have been poorly handled with skin oil residues triggering the additional layer of toning. Toning is another subject that I will write up over the (hopefully) quiet Christmas period. More importantly, the rules of PCGS’s Cleaning determination are as follows:
So, is the above coin suffering “surface damage”? I do not believe so and await PCGS’s opinion on the matter.
Following are a couple of examples of using acid to strip away surface in order to create “red mint” coins. Alas, no Australian half penny carries this sort of toning so the American Ebay Doctor that these were purchased from did a real botch job. PCGS rejected them outright as “Questionable Color”. The left is 1943M and is one of 3 different alloys that I’ve found in XRF testing – probably a Cu/Zn mix. On the right, the yellow metal colouring should be the reader’s clue to determining what alloy? You guessed it – phosphor bronze used in 1941. I’ve imaged the obverses as the interference is much more prominent than on the reverse sides.
Differentiating Metal Colour from Toning Colour
A refresher reading of the article published in the Australiasian Coin and Banknote magazine earlier this year might be useful following this article. For the above two coins of same date, the London minted coin is phosphor bronze, while the Perth half penny is displaying the tendency towards colour that is the hallmark of the Perth Mint. I’m inching closer towards an answer on the particular toning of Perth Mint bronze. However, for this article it is important to differentiate between the colour created by metal composition and that which toning imparts on a coin.
Towards a Better Understanding
The coin above has remained a mystery for these past three years I’ve owned it. PCGS labels it UNC Details Cleaned. From my self-learning to-date I can deduce the following:
The coin exhibits normal colour for its metal content (phosphor bronze) and toning colour – light gold with russet patches.
The reverse is a business die. I’ve confirmed this by finding die filled 4 date examples in my collection of circulation strikes (note the die fill in the last number of the date). I’ve layered an image of the date from PCGS MS64 Cert. 42518622 (one of 10 finest graded) and as you can see below, the partial die fill on that coin is married to the very faint outline of the larger die fill on the number 4 visible in my example. They are the same reverse die.
The obverse strike is superior to the finest graded circulation coins available for this date. How do we determine this? Take a look below at the crown jewel beads on the MS64 graded example linked above – there is no individual beading. Now take a look at the example in my collection.
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