Gold / Sovereigns / Checking / Fakes / Cleaning Gold Coins for Absolute Beginners
Newcomers entering the world of precious metal collecting might be tempted to dive straight in and buy some gold.
Everyone has heard of gold and that it is an expensive, valuable metal used in jewellery and regularly appears in television adverts as good for investment purposes.
Anyone can purchase a small piece of gold and take pride in showing it to friends and family so maybe the best way to lose your precious metals ( PM ) virginity is to buy a gold sovereign or half sovereign. These coins have been around for 500 years but for most of us we can say since Queen Victoria as it is unlikely, we can afford the earlier years.
Until you have in your hand both a half sovereign and a full sovereign there is a very high probability that you cannot tell the difference. Trolling a car-boot sale or an antiques shop, you spot a coin that someone tells you is a sovereign. Trust me, unless you have experience you may end up paying double the price for a half sovereign and if selling what you believe is a half sovereign ends up being a full sovereign !
Basic Data for Sovereigns and Half Sovereigns
A sovereign is not pure gold which is 24 carat.
Pure gold is very soft so to make a coin that is harder and will not mark easily, other metals are added and the mixed metal becomes an alloy.
The primary metals used are silver, copper and zinc.
The new alloy is now designated 22 carat ( 22 ct ) which is important to remember.
Why is that ?
When you Google the price of gold this is quoted in various currencies at the spot price. [ There are other prices like London am / pm fix, bid / ask etc. but let’s keep it simple ].
This is the traders’ value and it changes every few seconds.
Your sovereign has a weight and you can value your coin using the spot price BUT your sovereign is not 100% pure ( fine ) gold – it is 22/24 by weight fine gold.
Therefore your weight in fine gold is 91.66% - that is almost 10% less that you might have originally thought.
Sovereign specifications have remained the same since 1817, unlike many other coins, so you can safely reference the following table.
0.992 mm ( nominal )
Typical Range of Weights
7.94 – 8.02 g
3.84 – 4.07 g
Fine Gold Weight
Pictures are shown for the latest 2020 sovereign and note the coppery colour.
An early Victorian sovereign is shown with the shield reverse pattern.
Its colour is more of a yellow gold; what you may have seen in jewellery, other gold coins or museums.
Both coins contain precisely the same amount of fine gold per the table above.
The marked differences in colour are explained later.
You will come across the use of the following terms used in describing all coins.
The OBVERSE which is the side showing the Monarch
The REVERSE is the opposite side and for the majority of sovereigns features the iconic George and the Dragon; other than the Shield ( earlier Victorian era ) which was also used in the modern 2002 coin design.
When looking at other heavier coins ( and especially silver coins ) their weights are more often shown in Troy Ounces.
A Troy ounce is different to a normal ounce and is 31.104 grams.
To convert troy ounces to grams multiply by 31.104 and from grams to troy ounce divide by 31.104.
A sovereign weighing 8 grams is 0.257 troy ounces containing 0.235 troy ounces of fine gold.
As an example if gold spot is quoted at £1,397.76 per ounce that means it is £1,397.76 / 31.104 = £44.938 per gram.
A sovereign contains 7.322 g of pure gold so its spot value at the quoted rate ( which can rapidly change ) is £329
Essential Basic Equipment for Collectors & Stackers
If you are going to accumulate sovereigns or other precious metal coins, either as a hobby, or as an investment you should equip yourself with some basic tools.
Spending £100 is inexpensive to paying £350 for a fake sovereign !
Digital Electronic Weighing Scales
For sovereigns you ideally want a decent quality scale with a capacity 50 or 100 g so it has a good stable resolution of 0.01g.
The latter figure is the more important and you should avoid overloading a digital scale.
Initially I purchased 2 very cheap scales meeting these requirements but they were unstable and required taring every few seconds so to me too unreliable.
I subsequently bought a good quality 50 g scale, as pictured, which can also weigh 1 Toz ( 31.104 g ) coins.
Scales with higher capacity e.g. 100 g will enable you to accurately weigh 2 Toz silver coins like the Queens Beasts series.
I have a second scale, which was inexpensive, that will weigh up to 300g as illustrated, also with 0.01 resolution, but the last digit jumps randomly so I cannot rely on 0.01 accuracy.
Maybe 0.05 or slightly worse. Fortunately because I have both I can compare between the two.
I use the 300g scales for heavier coins and also if I wanted to make a specific gravity test - see later.
Never place a heavy weight exceeding the maximum capacity on sensitive scales or you can permanently damage them.
You can start with a really cheap scale ( eBay shipped from China ) that will cost only a few pounds or you can spend around £30 and get something more reliable and stable. The cheap scales tend to drift and are less stable meaning you are constantly resetting the tare ( this is the terminology for zeroing ) but you can get lucky and get something very useable for under £10.
The big question of course is how accurate are these scales ?
Normally pretty good but my advice is to buy a new or uncirculated sovereign and keep it as a “standard” meaning you will be able to check all future coins against your standard. Alternatively, a calibrated weight e.g. 10g kept handy if you suspect your scales are reading incorrectly. However the cheaper weight itself may not be 100% accurate.
As an example, if your uncirculated sovereign is truly 8.00 g but your scales read 8.02 g then store this coin and keep it as a “standard” for future use.
Although you don’t know that your scales are reading 0.25% high, you can periodically use your reference coin to check your scales are still performing as they did when new and haven’t drifted. This is particularly important if you ever obtain a coin that seems underweight – see fakes later.
This is an accurate engineer’s tool used to measure the diameter and thickness of all your coins.
You will read dimensions from an engraved scale or perhaps a dial or maybe a digital display.
Coin diameters are rigorously controlled and well specified so very easy to verify and spot any error.
Thickness is however nominal, and your callipers will only measure rim thickness – the highest points on the coin.
Sometimes on the odd coin its rim protrudes giving a false reading.
You may at some stage consider procuring a micrometer to measure more reliably coin thickness in several locations and near the centre.
A micrometer looks like the letter “G” and the coin is lightly clamped between its jaws to give a reading.
Since a coin has a cameo ( embossed pattern ) use an average measurement taken at several places.
Very useful in spotting fakes.
Note a Vernier calliper is also suitable for checking fakes.
If you set and lock the calliper gap to a specified coin thickness say 1.52 mm a sovereign, especially a coin with a little wear, must fit through this gap. Fakes never will but check for any unusual protruding rim before panicking.
Spotting Fakes This brief section is aimed at the majority of stackers and amateur collectors.
There are some fakes made with 22ct gold that would pass all these tests but fail on microscopic investigation due to minor differences in engraving.
These coins will tend to be for rare dates meaning they are much more expensive than regular bullion.
Only experts will spot the fakes and this article is for regular bullion coins only and not numismatic coins of high value and rareity.
Many stackers are naturally concerned about buying fakes. This is especially important to newbies with no previous experience so getting familiar with the very basic measurements is critically important. If purchasing a sovereign from a well-established reputable dealer then the risk is essentially nil but if you are reading this article there is every likelihood that at some future date you will be purchasing from unknown sources.
A good starting point is to have a genuine sovereign in hand to look at, feel it, weight it, note its colour and take measurements and compare with the table of specifications.
Spin it on a desk and listen to the tone as it settles – not essential but building some familiarity is recommended when starting out rather than diving in blind.
As mentioned earlier try to obtain a half sovereign and a full sovereign so you can familiarise yourself with both and not get them confused.
Most fakes will be difficult to detect just by looking at the coin so be ready to follow the steps outlined below. Weight Compare to the table.
I have included a range of weights that I found collecting many sovereigns over several years.
The weight of a well-circulated or well-handled coin will be slightly less than the specified value according to the amount of wear, especially on widely circulating bullion coins say 100 years old. These coins were used as currency and passed many times from person to person and carried in pockets or pouches, maybe rubbing together with others.
A low weight, outside the tolerance shown without noticeable wear is highly suspicious and requires further checks.
A higher weight isn’t going to occur.
Nearly all fakes will be underweight which is a good starting point.
Diameter Using the vernier callipers, the coin should be the correct diameter.
Anything larger say 0.5mm or thereabouts is highly suspicious.
A good fake will be the correct diameter so difficult to eliminate with this measurement.
Thickness Judgment is needed here because a precise thickness measurement is not really possible. This is due to the profile of the surface and also because a coin may have a variable rim. However, determining an average value is suggested avoiding the rim if it is protruding. A sovereign should pass through a gap of 1.52 mm and a slightly worn coin will pass through easily. Fakes will most probably fail this test.
In the early days there was a very simple sovereign tester usually made from brass as shown in the picture below.
This tester was a pivot balance with the coin placed into a circular well.
The coin had to fit so if its diameter was too great it was probably a fake.
If it didn’t tip the balance it was too light and therefore likely a fake.
Lastly there was a slot which the coin had to pass through.
If it didn’t then it was probably a fake.
These quick and simple tests were reasonably good because gold has a very high density meaning it has a low volume for a given weight.
A fake can be produced to the correct weight but using lower density materials, by the laws of physics, means it must have a higher volume.
Volume is the product of area and thickness so if the diameter is correct the coin must be thicker.
A good fake will always have the correct diameter because this is easily measured.
Since there isn’t an alternative base metal, or cheaper than gold metal, to substitute for gold, a fake will usually be both underweight and thicker trading between the deviations of both hoping they go undetected.
Having confirmed weights and dimensions another test for further verification which is difficult to cheat is the specific gravity test.
As mentioned the main unreliability of verification is thickness, so having a further test is worth considering although this is more involved and takes some care.
Specific Gravity Measurement This can get quite technical but essentially specific gravity is a number that determines the average density of the item being tested.
It can then be matched up to a table to determine the purity of possible gold and silver content.
Fine Gold 99.9% pure has a specific gravity of 19.3 and fine silver 10.49.
These numbers are also known as densities measured grams per cubic centimetre.
One quick and simple way to measure SG is to use precise electronic scales and carefully follow these steps in order.
This worked example was undertaken for a 1 oz fine silver coin
1. Weigh your coin on an electronic scale in grams and record the number e.g. 31.2g
2. Place a paper ( or lightweight ) cup ( e.g. vending machine ) on the scales and fill half full with cold water
3. Tare ( i.e. zero ) the scales
4. Make a cradle / simple cross using very fine thread leaving about a 30 cm length free to hold and suspend your coin.
Now dip it into the water ensuring it is completely submerged and not touching the bottom
5. Read the scales and record the number, e.g. 2.97g
6. Now calculate the ratio using your 2 numbers e.g. 31.2 / 2.97 = 10.5
7. Look up the value in the table below which confirms fine silver.
This is a fairly accurate measurement so you should be working within about 1-2 % error.
A fake will be way off the value by 10% or more.
10.4 to 10.6
10.9 to 12.7
12.9 to 14.6
15.2 to 15.9
14.7 to 16.9
17.7 to 17.8
Sterling Silver 0.925
10.2 to 10.3
This gets a little bit more complicated measuring a gold sovereign.
All sovereigns and half sovereigns are 22 carat gold which is exactly in the ratio of 22/24 by weight.
The other 2 parts of the 24 are either silver or copper or maybe even a mix of both and may contain a small amount of zinc.
A sovereign weighing 8.0 grams therefore will contain 22/24 x 8 = 7.333 g of gold with 0.667 g other metal.
There probably is a mathematical formula to calculate the SG of 22 ct gold but we cannot know the alloy composition to gain a precise number better than the table shows.
Whilst the SG test works well for silver due to it's relative low value and the possible cost of ensuring a counterfeit passes this test, it's totally different for gold which has a close density replacement in the form of tungsten.
The SG test alone cannot be used without other tests on gold bars where it is widely known that there could be centre rods of tungsten or maybe a thick plating of gold on a piece of tungsten. The price of tungsten is less than 0.1% that of gold so replacing cores of gold in larger bars can be extremely profitable for counterfeiters. Colour
Small quantities of silver lower the lustre / tint whereas copper greatly enhances it.
Older sovereigns alloyed with silver are a lighter yellow – more characteristic of the expected gold colour, whereas the new sovereigns look browner and have a high lustre that looks like a varnish coating.
Comparing the two types side by side would perhaps make a newbie think the browner coin is a fake.
The Mohs scale ( number range 1 – 10 ) is used to rank materials on their hardness with 1 being soft and 10 the hardest.
A material with a higher Mohs number can scratch all materials having a lower number.
Pure gold and silver are considered soft so that’s why other metals are alloyed to make them much more resilient.
Some examples –
Aluminum 2.5 - 3
Gold 2.5 - 3
Silver 2.5 - 3
Platinum 4 - 4.5
Steel 4 - 4.5
Malleability of Metals
Malleability is the ability to deform under pressure without breaking - compressive stress used in pressing coins during the minting process.
A high malleability means the metal will form and take up a pattern much easier than a low malleability metal.
Gold is the most malleable of all metals.
A gram can be beaten into a sheet of 1 square meter.
Gold leaf is thin enough to become transparent.
Silver is also very malleable.
Due to its hardness and that tungsten can be very brittle unless very pure, tungsten is a difficult metal to work compared to others.
Gold is inert and will not tarnish or rust. This means that there is almost no chemical agent, acid, solvents, detergents etc that will harm gold making it easy to clean grubby coins. Ultrasonic cleaning is a vibration method of shaking off dirt that has accumulated in grooves and on the edges of features. This is a good way to clean coins.
Because sovereigns contain other metals like copper, strong acids may affect a coin by dissolving or reacting with the alloys.
There is an acid mix called Aqua Regia that will totally dissolve gold and is used in recovering gold from electronics etc.
This is a mixture of approximately 25% concentrated nitric acid and 75% concentrated hydrochloric acid which is a highly active cocktail with a short shelf-life as it decomposes quickly releasing toxic gases.
Possibly the best way of cleaning a grubby old bullion sovereign is to use a soft toothbrush and scrub it in hand hot water with washing up liquid.
Proof coins are minted in a different way to regular bullion coins and many sellers on especially eBay describe shiny looking coins as proofs when they are not.
A proof sovereign has an incredibly sharp cameo with very sharp detail contrasted against a highly polished background.
Many proof coins purchased from eBay and even popular dealers unfortunately can have finger marks or greasy stains and spots – just breathing on one of these coins can affect it. Small damage and fine scratches are easily spotted when viewing a coin at a grazing angle of incidence in strong light. Some people are tempted to dust a proof coin and even using a soft haired brush, if the dust particle like a tiny speck of sand is wiped across the gold surface it will leave a scratch – remember the Mohs scale !
It is not advised to attempt to clean proof coins or coins with any premium over bullion. However, if you have obtained a nice proof at near bullion price which has fingerprints or spots then you may wish to try and remove these marks. Because nothing can harm gold you can experiment with solvents and cleaning agents but introducing fine scratches is a real possibility. A suggested method for removing or partly removing finger marks and handling spots is to prepare a shallow bath of acetone and holding the rim of the coin submerge and oscillate the coin so the surfaces are washed in the acetone. Rinse in running water and immediately pat dry using a soft paper towel. Do not wipe or rub prior to rinse washing as microscopic grit will leave hairline scratches. If there are still marks present, then you may try a small amount of “Peek” or chromium metal polish on a cotton bud and see if you can remove the spot or stain. Wash in detergent using the wave method, then wipe with a wet soft cotton ball if necessary, before immediately patting dry.
What is a Good Price for a Gold Sovereign ?
A regular bullion gold sovereign is no more than 7.322 g of pure gold which most bullion dealers and coin sellers’ price as scrap metal.
That seems pretty unfair but the dealer wants to sell your coin and has to cover costs and hopefully make some profit. There are however some sovereigns that have either a unique reverse design or are scarce so prices will vary enormously. Leaving those aside a dealer will value your gold at around 97-98% of spot at the time you are seeking a quotation or checking on-line. Buying the same sovereign will likely cost you spot + 5% or maybe even more. That means the dealer is working on a spread of around 8% in this example.
This is the situation at the time of writing this article with gold at a historic high price. There is global panic due to Coronavirus-19 and gold is being bought by the bucket load so dealers are able to squeeze more margin out of panicked buyers who don’t seem to care too much about the price – just get me some gold !
Buying and selling on the SilverForum will typically see a sovereign sold and bought close to spot or maybe spot + 2 % or thereabouts.
Several years ago, a typical dealer would buy your gold at 98.5% of spot and sell sovereigns for spot + 2% meaning their spread was less than 4%. That doesn’t happen any longer with these dealers, so as a guide buying one or a small quantity of sovereigns expect to pay spot + 5%, or less if prepared to buy from private sellers and forum members.
As for proofs then 10 years ago you might expect to pay 20 - 30% or more premium for a proof. Today there is very little difference in ‘value’ compared to bullion. However, many dealers will list their proof coins and boxed coin sets at bullion prices + 50% or much more because they can and someone might naively pay their price, not caring because the date or set is for a special gift where the intrinsic value is of no consequence. Selling even a low mintage boxed proof set of gold sovereigns to any dealer you will be offered scrap value only so be careful when choosing your gold.
"Happy Hunting" and use the forum to ask questions and look out for gold bargains which you will definitely miss unless you are a Premium member.
All the best deals happen very quickly on the forum and listings are hidden for a couple of days to give Premium members first viewings and good deals will be snapped up.
Further Detailed Information on Sovereigns
Should you have a more serious interest in sovereigns and need detailed information about the many variations, dies, mints etc. there is a good reference book available.
This is not ‘comfort’ reading but for serious collectors it is probably the best.
Author is Michael Marsh and the ISBN 978-1-908828-36-1 revised 2017.