Is this gold coin authentic?

[MythicQuale]

The 1oz 2021 Britannia gold coin has just arrived; really happy! The weight seems fine, but I thought I'd give it a ping test with the only Android app that supports the 1oz Britannia gold coin, which is "Bullion Test" (It's actually the 2014 Britannia version in the app, but I presume that's similar to the 2021 Britannia coin). I find it hits all the correct frequencies give or take, EXCEPT unfortunately the last frequency around the 19k mark which is missing from my coin. I tried it a few times, and it was always missing. Is this okay?

Also, the coin has a sharp feeling around near the edge of the perimeter on the main (non-head) face. The edge is sharper on one half of the coin than on the other half, like as if the sharp ridge is fractionally 'taller', and on the opposite end of the face is flatter and more flush with the rest of the coin. Is this also okay? 

In the chart blow, the blue lines represent the expected frequencies, and the white lines represent the recorded frequencies from my coin - I'd be really grateful if someone else could test their Britannia 2021 to see if they get the same result:

Here's a picture to illustrate the sharp edge of my coin. Please tell me I'm being hyper paranoid

[Simmoleon]

Doesn’t this coin have the new RM security features? Have you checked these are present?
 

Did you get the coin from a reputable dealer? Also do you have a clear picture of the coin obverse and reverse?

thanks

Steve

[MythicQuale]

Hi Simmoleon,

Yep as far as I can tell, the security features are indeed present. The small hologram is there and the waves show up at some angles in the light (and differently in other angles). I tried to take some close ups below. Hope you find them useful.

Yes, a reputable dealer and even has a proper shop in the UK. I didn't buy from the Royal Mint, but the mini box it came in has a yellow cap with "The Royal Mint" written on it, so I presume the dealer obtained it from them.

In the first photo below, the sharp edge is very noticeable at 10 oclock, and gradually tapers to flat as it goes around to 4oclock. Great photo to illustrate this.

 

[Arganto]

Not to poop on these kinds of applications but you're asking a minted piece of metal in the tactile 'analogue' world to conform to a set of digital expectancies. That and the microphone on a mobile device, even fitted to the best ones, is a compromised built to a budget piece of Chinese hardware. If you had a decent microphone, operating in ideal conditions attached to a competent sound board running into a computer set up for audio recording I may have more confidence in this method of testing. Otherwise it's dimensions, weight, comparison to other coins of the same design and if you're really unsure specific gravity testing and a metal analysis. That will get you by with everything except maybe super rare/unusual coins or something made by a master forger...

*Also, I'd say it would be super duper unusual to get a brand new coin from a reputable dealer that was dodgy. I'm not saying skip due diligence, but it's usually things like older sovereigns that may present an issue.

 

[MancunianStacker]

13 minutes ago, Liam84 said:

*Also, I'd say it would be super duper unusual to get a brand new coin from a reputable dealer that was dodgy. I'm not saying skip due diligence, but it's usually things like older sovereigns that may present an issue.

This and the fact it looks sound.

Cant see the Chinese having copies looking as good as this “out” already when there are literally hundreds of other coins they could copy/fake.

Pretty sure its legit 👌 

[Simmoleon]

Apologies about the late reply but if it has the security features and came from a reputable dealer I’d be very confident in its authenticity because it’s very unlikely anybody could fake these to any decent or consistent standard. Far easier coins to fake as well.

Obviously you could rest the metal itself but from what you have posted I would expect this to be genuine 

[stefffana]

I think your coin is genuine, but is one of the kind, with an error. Maybe in time will be very valuable, who know?

I suppose the sound test failed because the shape error. Do a gravity test, drink a glass of red wine and relax.

Cheers.

Stefan.

[Mike1976]

Forget the phone app and trust your eyes. The security features are present and the coin looks beautiful from the photos. And it’s already been said that there are plenty other gold coins that are easier to fake than the 2021 Britannia. 
 

[MythicQuale]

Thanks all for your reassurance! Can't do the density test right now, since my most accurate scale is only accurate to 1/10th of a gram. I'll be getting a *very* good microscope soon, so I'll take a good look at that micro lettering when I do and post a photo here once I'm done. Just for fun really since I'm fairly convinced it's genuine 

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That and the microphone on a mobile device, even fitted to the best ones, is a compromised built to a budget piece of Chinese hardware.

I guess I was more curious if the missing frequency is something that others have experienced in the 2021 Britannia 1oz coin as I suspect and hope is the case. I might have to try to obtain a Baird (rather than RoyalMint) minted 2021 (and 2014) coin somehow to check that theory.

Bear in mind, the crappy microphone DOES pick up in small amounts all frequencies around  18-19k (as shown in the attachment), so it is capable of detecting around that range. I ping tested numerous times and although the other main gold spikes (3.4, 3.7, 8.2, 14 and 14.1) jumped up and down depending on where and how hard I hit the coin, there was never a glimmer around the remaining 18-19k mark.

[fearlessjs]

Hi MythicQuale,

I'm pretty sure the frequency around 18 kHz for the gold 2021 Britannia is a mistake on part of the (otherwise excellent) BullionTest. The app also seems to be missing the last frequency which you have at 21 kHz. I've not added the gold Britannia to my app testing app (Pingcoin) because I typically wait until I have enough coin recordings that I can accurately determine thresholds for the variance you always see in coin resonance frequencies. Which currently I unfortunately do not have.

Based on the two recordings I have for the 2021 gold britannia the frequencies compared with yours look spot on:

	Pingcoin #1	Pingcoin #2	You
c0d2a	3341.00	3377.00	3380
c0d2b	3627.00	3597.00	3639
c0d3	8143	8056	8096
c0d4	14021	13971	14018
c0d5	21190	21035	21210

This is also consistent with my physics modeling of a 32 mm diameter pure gold coin, which shows there might be a peak at the top end (21-22 kHz), but there shouldn't be anything around 18kHz.

[stefffana]

7 minutes ago, fearlessjs said:

Hi MythicQuale,

I'm pretty sure the frequency around 18 kHz for the gold 2021 Britannia is a mistake on part of the (otherwise excellent) BullionTest. The app also seems to be missing the last frequency which you have at 21 kHz. I've not added the gold Britannia to my app testing app (Pingcoin) because I typically wait until I have enough coin recordings that I can accurately determine thresholds for the variance you always see in coin resonance frequencies. Which currently I unfortunately do not have.

Based on the two recordings I have for the 2021 gold britannia the frequencies compared with yours look spot on:

 

	Pingcoin #1	Pingcoin #2	You
c0d2a	3341.00	3377.00	3380
c0d2b	3627.00	3597.00	3639
c0d3	8143	8056	8096
c0d4	14021	13971	14018
c0d5	21190	21035	21210

This is also consistent with my physics modeling of a 32 mm diameter pure gold coin, which shows there might be a peak at the top end (21-22 kHz), but there shouldn't be anything around 18kHz.

I am lost already... I feel so old!!!... But I believe you. 😁😂😃😄😅😀

[MythicQuale]

fearlessjs,

Haha, you're only increasing my trust in this "coin ring" app technology. Seriously, wonderful job.

Any chance of including a 1oz platinum Britannia too? I think the Britannias are the most popular coins in the UK, so it makes sense to include as many as possible, including the 1/4 and 1/10th oz coins if possible too.

I do have one more puzzle. Received the 1oz 2021 platinum coin from the royal mint today, and despite both the gold and platinum coins have the same diameter and same weight, and despite platinum metal being only 11% denser than gold metal, it seems like the gold coin looks much more than 11% thicker. By my estimates (measuring pixels in a paint program), it's more like 30% and at least 20%. I expected about only 10% thicker. Any idea what gives? Photo below: 

 

[Arganto]

I'll leave it to your own choice of hobbies, but you are expecting way too much out of the technology being used here. Most of it looks like a red herring from both a hardware and coding stand point, a way for application designers to make money. I'm not saying work hasn't gone into these things, but from an sound engineering point of view it's like having a soap box racer with a lawn mower engine strapped to it and calling it a Rolls Royce.

As for the thickness of platinum vs gold, there are good videos out there for this. I'm pretty sure it was @BackyardBullion that did some really good ones at some point.

[MythicQuale]

1 hour ago, Liam84 said:

I'll leave it to your own choice of hobbies, but you are expecting way too much out of the technology being used here.

I was originally skeptical, but honestly, it's (if anything) more promising than I expected. There's one way to prove it's not an ideal test. Just find a single false positive or false negative - i.e. ONE fake that passes the test, or ONE real gold coin that doesn't (read fearlessjs previous comment to show that the app I used was mistaken in the top 19k Hz frequency; - with the correction to 21.1k Hz, my Britannia coin would show as genuine, which it is).

As has been shown and said, gold coins filled with tungsten will not ring. Coin ping apps appear to recognize this well, if not on the very first attempt, then on the average of 3-10 attempts which takes minutes if not seconds.

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 I'm pretty sure it was @BackyardBullion that did some really good ones at some point.

Has that just alerted him? Hopefully he (or someone else) can shed some light on that.

[fearlessjs]

11 minutes ago, MythicQuale said:

There's one way to prove it's not an ideal test. Just find a single false positive or false negative - i.e. ONE fake that passes the test, or ONE real gold coin that doesn't (read fearlessjs previous comment to show that the app I used was mistaken in the top 19k Hz frequency; - with the correction to 21.1k Hz, my Britannia coin would show as genuine, which it is).

There is one type of counterfeit a digital ping test won't protect you from. Some coins have historically been counterfeited by using the same metal composition (e.g. pure silver/gold) just to cash in on the premium. If properly cast, those counterfeits would have the same resonance frequencies as the authentic version. That said, you'd also still own actual gold/silver if you got fooled.

You can generate false positives with a digital ping test because the frequency profiles of coins aren't 100% unique. It's sort of like a wooden flute and a brass flute being able to hit the exact same note. 

The golden kangaroo will pass as a silver kookaburra for instance, and vice versa. 

But for a counterfeit to look like a golden kangaroo and pass like a golden kangaroo isn't possible. 

The same for a silver kookaburra.

Also, because there's variance in the spread of the frequencies, each app is going to either have to accept some false positive or false negatives. If you make the thresholds too narrow, you'll exclude certain authentic coins from authentic verdicts. Gold and silver maple leafs both have high variances in their peaks, it wouldn't surprise me if you can generate a false negative with those.

[MythicQuale]

All good points. I guess I meant ideal when combined with the density measurement, or at least ideal for my situation where I'm just testing for gold where only tungsten is a potential concern.

Quote

That said, you'd also still own actual gold/silver if you got fooled.

True, I was thinking more of the raw value of just the pure metal (for investment purposes) rather than historic or detail value on the face itself. 

Quote

You can generate false positives with a digital ping test because the frequency profiles of coins aren't 100% unique. It's sort of like a wooden flute and a brass flute being able to hit the exact same note. 

I'm guessing this wouldn't be an issue for gold because of the ping+density test combo, but yeah for silver or other metals it could be more problematic.

[MythicQuale]

For anyone who's curious about the platinum versus gold thickness, I bought a precise digital caliper with a 0.01mm resolution and took 10 measurements each inside the 'circular wall' for both of the coins (since the tip of the caliper was able to fit inside), and the summary is the platinum coin averaged about 1.97mm thickness, and the gold coin averaged about 2.14mm thickness. So it is within expected range after all (since 2.14 is 8.6% thicker than 1.97, and we're expecting the gold coin to be 11.3% thicker due to platinum's greater density, but eh, close enough).

Both weighed 31.3 grams and the diameter was the same at around 32.7mm (+- 0.02mm).

From my previous photo, the gold coin looked way more than 8.6% thicker (more like 25%), but I'm almost certain that's because I was measuring the part of the coin with the higher wall (the thin sharp edge, which goes back to the issue from my first comment). Obviously, we shouldn't be measuring the thin sharp wall, since that's misleading for the majority of the average thickness of the coin.

Case solved!

[LawrenceChard]

On 17/02/2021 at 12:01, MythicQuale said:

I do have one more puzzle. Received the 1oz 2021 platinum coin from the royal mint today, and despite both the gold and platinum coins have the same diameter and same weight, and despite platinum metal being only 11% denser than gold metal, it seems like the gold coin looks much more than 11% thicker. By my estimates (measuring pixels in a paint program), it's more like 30% and at least 20%. I expected about only 10% thicker. Any idea what gives? Photo below: 

 

Oh, no, don't tell me the Royal Mint have started supplying cheap Chinese fakes now!🙂

[LawrenceChard]

On 16/02/2021 at 14:45, MythicQuale said:

Also, the coin has a sharp feeling around near the edge of the perimeter on the main (non-head) face. The edge is sharper on one half of the coin than on the other half, like as if the sharp ridge is fractionally 'taller', and on the opposite end of the face is flatter and more flush with the rest of the coin. Is this also okay? 

Here's a picture to illustrate the sharp edge of my coin. Please tell me I'm being hyper paranoid

 

Sounds like typical Royal Mint quality, so I don't think you have anything to worry about! 🙂

I would not place much reliance on "ping" tests, there are many factors which could minor or major effects on the sound frequencies of genuine coins. It the app could let you save numerous tests, and perhaps annotate them, you could build up experience of typical variations, which could be helpful. I would not take any "bad" result as being "wrong" or indicating a fake, rather an alert to look more closely.

Being my usual pedantic self, you have referred to the non-head side as the main side. In minting and numismatics, the rulers head is always the main side, and is called the obverse. The other side is the "reverse" (not the backside!). In countries and states which do not have a ruler, the obverse is usually the side which identifies the state or issuing authority, and the reverse usually contains the finer details, such as denomination, date, weight, fineness, etc., although this scheme is not absolute or universal.

I am happy to oblige by responding to your request to be told you are being hyper paranoid, even though you probably aren't.

Here is a page of one of our "legacy" websites which helps to explain more about obverse and reverse, heads and tails:

https://24carat.co.uk/headupsidedowninvertedreverseframe.html

 

[Foster88]

On 16/02/2021 at 14:45, MythicQuale said:

The 1oz 2021 Britannia gold coin has just arrived; really happy! The weight seems fine, but I thought I'd give it a ping test with the only Android app that supports the 1oz Britannia gold coin, which is "Bullion Test" (It's actually the 2014 Britannia version in the app, but I presume that's similar to the 2021 Britannia coin). I find it hits all the correct frequencies give or take, EXCEPT unfortunately the last frequency around the 19k mark which is missing from my coin. I tried it a few times, and it was always missing. Is this okay?

Also, the coin has a sharp feeling around near the edge of the perimeter on the main (non-head) face. The edge is sharper on one half of the coin than on the other half, like as if the sharp ridge is fractionally 'taller', and on the opposite end of the face is flatter and more flush with the rest of the coin. Is this also okay? 

In the chart blow, the blue lines represent the expected frequencies, and the white lines represent the recorded frequencies from my coin - I'd be really grateful if someone else could test their Britannia 2021 to see if they get the same result:

Here's a picture to illustrate the sharp edge of my coin. Please tell me I'm being hyper paranoid

Welcome to the world of Royal Mint defects.

I’d be most concerned handling this coin with bare hands but maybe that’s just me. 😬

[Pablo86]

Quote

On 16/02/2021 at 14:45, MythicQuale said:

The 1oz 2021 Britannia gold coin has just arrived; really happy! The weight seems fine, but I thought I'd give it a ping test with the only Android app that supports the 1oz Britannia gold coin, which is "Bullion Test" (It's actually the 2014 Britannia version in the app, but I presume that's similar to the 2021 Britannia coin). I find it hits all the correct frequencies give or take, EXCEPT unfortunately the last frequency around the 19k mark which is missing from my coin. I tried it a few times, and it was always missing. Is this okay?

Also, the coin has a sharp feeling around near the edge of the perimeter on the main (non-head) face. The edge is sharper on one half of the coin than on the other half, like as if the sharp ridge is fractionally 'taller', and on the opposite end of the face is flatter and more flush with the rest of the coin. Is this also okay? 

In the chart blow, the blue lines represent the expected frequencies, and the white lines represent the recorded frequencies from my coin - I'd be really grateful if someone else could test their Britannia 2021 to see if they get the same result:

Here's a picture to illustrate the sharp edge of my coin. Please tell me I'm being hyper paranoid

 

Same mine 2021 Britannia bought from reputable dealer. 5/6 frequencies matched and sharp edges. Nothing to worry about