[1] Sigma Metalytics PMV PRO - Introduction & Review 

this device measure the thickness too

There is this thing called Ultrasonic Thickness Meter (UTM) It's less than $200 Go to ''Basics of Testing For Silver and Gold...'' to learn about metal properties and the testing methods for each property. Very informative. I use the UTM and caliper verification test as my go to #1 test method. Then the Specific Gravity test for fun. An UTM is absolutely necessary for big bars authentication process. I do not have confidence in the sigma basic or pro verifier as I don't know the science behind it's claimed test functions. Do they only do surface ECM analysis or through-the-metal test, as they claimed? The optional bridge on the Pro is nothing more than 2 sets of rulers and a digital drop gauge. FYI. The density/specific gravity test is not conclusive either, whereas the ultrasonic celerity test IS, in my opinion. Plus you should at least do 2 tests for greater verification of your metal. FYI. The UTM is best for 0.999 metals, but can be a useful tool for 0.9 or 0.9167 metals.

@@ghaithdarwish822 internally or just externally. You don't need to pay $2000 for what a $10 tool can do just as well.

XRF scanners are useless for through-checks as the X-rays only hit the surface metal a few microns thick (not even milimetres thick). The scanners work on the basis of excitation (Fluorescence) when X-rays hit the surface metal. A tungsten filled bar or coin would easily fool an XRF device. Further I seriously doubt a coin dealer would allow you to use a Niton gun to blast some x-rays on his coins for checking. The most accurate method is by using ultrasound techniques (gauge or through reader - the same device use to detect thicknesses or flaws in metal) of which bullion banks use for gold bars. However this would be impractical to bring to a coin shop for testing coins during a purchase as no coin dealer would allow you to slap on couplant (gel) on their coins or bars. The SMPro is the most practical tool to use when purchasing coins and bars from a coin shop or bank. In addition to resistivity measurements to screen out tungsten, the Pro allows immediate density checks which should screen out any copper filled bars and coins. Check it out : ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-89ATeNy3DIo.html . This one should scare you : note at 2:46, the XRF devise came back with pure gold for a fake tungsten coin coated with gold ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-YR_1xaWBeZ4.html

XRF can be defeated if you are a bit generous with the gold plating. A layer 0.5mm thick or greater is sufficient to pass XRF detector.

@@michaelc7302 How does the SMPro do the density check?

@@ptaeiy No. You have to input the metal type say 9999 gold. The resistivity measurement is through a coin and so it works out the thickness knows the density and then works out the diameter of the coin. Please go here www.sigmametalytics.com/pmv-videos-improved please note tungsten has a different resistivity value to gold.

@@michaelc7302 I wasn't too concerned about the ECM part of the testing. I'll take their word that it's a ''through-the-metal'' electromechanical wave test. It should be ok for coins and small bars. I was asking about how does SMPro 1) ''measures'' density? 2) ''measures'' thickness? From your reply, I'll deduce the ''thickness' , 'diameter' and 'density' values on the SMPro are done by applying such formulae as D=M/V; V=Ah; D=2(sq root of V/pi) after asking the user to separately measure using calipers and worse still by eyeballing/approximating it on that bridge thing, which looks like 2 sets of rulers and a digital drop gage. As such the arrived at values for h=thickness and D=density is purely ''expected'' values per the formula, and not any actual active measuring of the test samples. Do the SMPro also ask the user for the sample weight? This is not even close to justify paying $2000 for something I can do with MY calipers and scales and a calculator which I can buy for under $30. A through-the-metal thickness measurement (ultrasonically) will give me the highest confidence of the metal content(s). If you had done any volumetric density calculation, you'd know that it's very very imprecise as your caliper is not designed to account for the topography and rim of a coin. Unless you have a laser scanner, any dimensional measurement using calipers will be way off that it'll give you very distorted density value. I would guess that SMPro collected Specific Gravity Density data from the many ''popular'' coins, and then average them out after adding say about 30% to the calipers measured dimension. This poor methodology may satisfy some into paying the $2k, but what if I had a totally different coin say a high relief coin that needs a 50-60% volume compensation. Then the SMPro ''expected'' volume and density values will be outright wrong. And if I had relied entirely on SMPro to authenticate my metal, I may be compelled to drill holes or cut into my coin.

Silver Eagles are only 3 nines silver (99.9) Small contamination in the 0.1% can increase resistivity. Are you using the right setting for 99.9 on the machine? This deviation from pure silver get me worried about really good fakes, that nobody has seen before. This is why I prefer Canadian maple leaf which is 4 nine silvers. (99.99%) Silver has the lowest resistivity of any known metal, so faking 4 nine silver is next to impossible.

The PMV PRO can test 90% silver coins, however it is a little trickier than testing other standard alloys. US silver coinage is nominally 90% silver and 10% copper, however the alloy frequently contains trace amounts of other metals like tin and lead, which throw off the electrical properties. Generally the older the coin, the more impurities, so the PMV PRO has three date ranges for 90% coin silver: pre-1900, 1900-1945, and 1945+. The newer the coin, the more consistent the alloy, and the narrower the testing range. Even with those varied ranges, we have found some genuine 90% coins that fall into the red zone. However, the counterfeit 90% coins we have tested have resulted in numerical values of 7 or greater, where the genuine 90% coins typically read 2.5 or less, even when they cross into the red zone. So the PMV PRO does provide useful information when testing 90% coins, and at least for now, there is a large enough difference between the genuine and counterfeit alloys to distinguish them numerically. Neither the original PMV nor the PMV PRO can test war nickels.

Actually the original (and possibly Pro) should be able to test a war nickel using measurement mode. You just need someone with a genuine one to give you a range of readings it gives, so you know what is correct.

No, the PMV is completely non-destructive.

Checking the weight and dimensions is really a way to check the density of the metal. Gold is very dense, and the only practical way to match the density of gold in a counterfeit is with tungsten. A gold plated tungsten fake could be the correct size and weight, but the PMV will show the much different electrical properties. A copper fake could pass the PMV test, but copper is much less dense than gold, so either the size or weight of the item will be wrong. Whether you are using the original PMV or the PMV PRO, you still need to weigh the item on a scale to confirm the weight. With the PRO, you can check the dimensions directly on the device. With the original PMV, you'll need to use calipers to measure the dimensions, and you'll either need reference material to see if the dimensions are correct, or you can do a calculation to determine the density and see if it matches the expected value for gold (or silver). The bottom line is this: check the weight, check the dimensions, and use a PMV. A counterfeit could pass any two of the three tests, but there is no known counterfeit at this time that can pass all three. The PRO makes it easier to check the dimensions so you don't need another tool and reference material (or math), and also gives you more feedback with the through measurement to help detect plating. But if you are buying mostly known items that you can find reference information for, and/or do your own density calculations, then using the original PMV along with a digital scale and calipers should keep you safe.

The resistivity of platinum is 1.06×10−7, an order of magnitude larger than the resistivity of gold. An alloy containing sufficient platinum to match the density of gold would read "right arrow" on the original PMV and far to the right in the red on the PMV PRO. Uranium is obviously more expensive and more difficult to obtain than tungsten or platinum, and has a much higher resistivity. Uranium is not a realistic candidate for manufacturing counterfeit gold, and even if it were, it would not pass the PMV test.

@@FakeBullion How about a clad coin. Iridium core (higher density than gold) copper jacket (lower resistivity than gold) and gold plating?

​@@nickl5658 The resistivity of iridium is more than twice that of gold. The bridge sensor on the PMV PRO reads all the way through the thickness of the coin. So even if the copper jacket was alloyed to match the resistivity of gold and was thick enough to match the surface reading for gold, the through reading would still be far outside the expected range, way off to the right. Even the "surface" reading on the PMV penetrates the metal deeper than an XRF, so it would be a challenge to achieve a sufficient copper alloy layer to fool the PMV surface reading while still getting the overall density of the coin correct. Plus given the complexity of this hypothetical coin and the cost of iridium, a counterfeit made this way would end up costing much more than an ounce of gold.

The PMV Pro has the refiner's wand which checks deeper than the bullion wand from the original PMV. Also the PMV Pro's through testing I assume is better than the oiriginal PMV can do. Really thick silver and gold bars (e,g, > 20 oz) are probably more risky with either.

I can show you the picture of the testing. Please help

The assay cards on some of the small, genuine Perth and Pamp bars are too thick to fit under the Small Bridge Sensor, so that alone does not necessarily mean the bar is fake. Sigma Metalytics recently revised the Small Bridge sensor to be slightly taller to accommodate those assay cards, so they will fit on newer PMV PROs. On older PMV PROs, the most reliable way to test the 10g bar is to remove it from the packaging and use the Small Bridge Sensor, and check the weight and size.

@@FakeBullion thank you for replying. As I said, I have 10g gold bar from Perth mint. Your video told that the only small bars that won't fit is 20g one so it worried me so much. So... like I said, I had to test with the bigger lense, and it showed green on through test, yellow on surface, and green on size test. What is your confidence level in this testing on this? I can email you the pictues...

@@LOL-ho4rt The metal must cover the entire sensor for an accurate measurement. The 10g bar is too small to use the Large Bridge Sensor. The Large Bridge Sensor will not provide an accurate measurement. So I cannot judge anything from the information you provided. You would have to remove the 10g bar from the assay card and test using the Small Bridge Sensor for an accurate measurement. The only information I can provide you is an example of a counterfeit 10 gram Perth Mint bar. I measured the counterfeit plastic assay card "bubble" that holds the bar to be 4.29mm thick and total weight in assay card 17.42g. Unfortunately, I do not have a genuine 10g bar here to compare.

@@FakeBullion thank you very much... always a big time fan of your video. And I had to re watch your video multiple times to tell if my collections are real. By any chance, do you have readings with bigger lense on your fake bar as well... I wanna know if the machine is giving you the not so accurate results.I really appreciate all the information in your video to educate small investors here. I always get my bars from a legitimate source but it was little different this time. Again, thank you very much !!! You are one of the few channels that is actually helpful and make the whole youtube platform great.

We have not heard of any complaints about major online dealers knowingly selling counterfeit coins or bullion.

They would be out of their minds to sell fakes. Their businesses would be wrecked.

I don't have any high relief slabs to check. The maximum thickness for the large bridge sensor is 13.5 mm. Hope that helps!

There is usually some variation in the weight of mass manufactured precious metals, particularly silver. A troy ounce is 31.10 grams, but even genuine bars and rounds will often weigh a little more. This is due to manufacturing tolerances and because it is more cost effective for the manufacturers to give away a few cents worth of extra silver than it is to scrap the piece and start over. Measuring the weight and dimensions is really a way to check the density of the metal. Currently a fake can match the electrical properties of the real metal (as measured by the PMV), OR the density of the real metal (determined by checking the weight and dimensions), but not both. You can calculate the density even if the piece is slightly over the stated weight. Pure gold is 19.30 g/cm3. Pure silver is 10.49 g/cm3. Pure copper is 8.96 g/cm3. Brass, which is what most fakes are made from, is even less dense than pure copper. I just weighed a half a tube of 2012 silver eagles and they ranged from 31.15 to 31.36 grams, all genuine. Buying from a major online dealer minimizes the risk of receiving counterfeits. Most counterfeits are sold by individuals through Craiglist, eBay, selling apps, etc. They do sometimes show up in the secondary market at pawn shops or, on rare occasions, at coin dealers who are not familiar with the recent influx of fakes. Make sure your favorite local coin dealer knows about FakeBullion.com and keeps up with modern detection methods.

Other than the through resistivity of the Pro, the other features seem to be merely convenience and all things you can do with the original model yourself (dimensions with calipers, weight with scale). The Pro just seems to make it automated and quick, which is very valuable for a coin shop, but for an individual maybe not worth twice the price. I've noticed that you have to read the manual carefully to be sure you're using the right wand/sensor and using the calibration disk if necessary.

I hear ya!

I suspect it is using ultrasonics.

It is Resistivity not ultrasounds. There is more explanation in Sigma website. www.sigmametalytics.com/instructions/pmv-pro- videos.html The interesting feature of the latest model is the ability to measure the Resistivity through the the sample. As far as I was aware up to now only ultrasound could test through the sample. So this is a major improvement to the previous models.

I read it was electromagnetic and watched the inventor describe it ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-v_6XbbuDc9U.html

No tester is perfect. Stick to items not in plastic packaging or really thick and the original PMV is entirely sufficient.

l'll buy it off you for $250?

That bar is too small to use the Bullion Wand, and if the bar is made of a sufficient copper alloy, it can read as gold on any of the sensors. It is very important to always check the size and weight (density) of the item, even when it reads within the expected range on any PMV device. Generally a fake can match the PMV reading, or the density, but not both.

@@FakeBullion Thank you! And in general the bullion wand? Isn´t it much more reliable than any other sensors of the regular tester? I´ve ordered especially a bullion wand because it comes 2mm through the metal instead just 0,2mm ... actually it´s a good idea to always use the bullion wand right? What would be too small for it? Everything thinner than 2mm ?

​@@ch.wey.4406 The Bullion Wand does penetrate into the metal deeper than the other Original PMV sensors. The piece you are testing must fully cover the face of the sensor/wand. So for the Bullion Wand, the item must be at least 24 mm in diameter/width. Additionally, to test samples with the Bullion Wand and without using the calibration disk, pure silver must be at least 4.0 mm thick, silver alloys and pure gold must be at least 4.5mm thick, and gold alloys, platinum, and palladium must be at least 7.0 mm thick. If the sample is thinner than that, you must place the sample on top of the calibration disk and then place the wand on top of the sample to get an accurate reading. But the sample must still be at least 24 mm in diameter / width. At this link you can read the PMV Original User Guide, PMV Original Technical Guide, and PMV Original Sensor Selection Chart for more information on the Bullion Wand: www.sigmametalytics.com/manuals

@@FakeBullion Great informations! Thank you! And a last question. For me as a private user... does it make sense to have a pro version? I have a lot coins and bars and I´m buying a lot at official gold traders. But for what I´ve bought the regular tester was to buy on the private market. As you said acutally the regular tester should be okay if I double check the coin or bar regarding to it´s dimensions right? I mean there must be a good reason for the decision to buy the regular one or the pro version and I´m not sure about that. If the pro version is the "perfect device" actually nobody should buy the regular tester. I´m still a little bit confused :-) Sry for that

@@ch.wey.4406 The Original PMV is usually sufficient for collectors and private users. The PMV PRO measures dimensions for you, instead of manually using calipers. The PMV PRO can also measure the thickness of some items in assay cards and numismatic slabs without opening the packaging. But the PMV PRO is higher cost than the Original PMV. So the PMV PRO is good for coin dealers, pawn shops, and other high volume users who test many items. Sigma Metalytics recently announced a new model, the PMV PRO Mini. The Mini has many of the features of the PRO, but it uses Android or iOS device screen over wifi instead of having a built-in screen. The price of the PRO Mini is in between the price of the Original PMV and the PMV PRO. We will make a video on the new PMV PRO Mini soon.

The optional wands can be used to check larger bars. The Refiners Wand can read ~2.5mm into the bar (minimum 24mm diameter to cover the face of the sensor). The MicroWand only reads about 0.1mm into the bar but can be used on small items. Coupled with checking the size and weight, these can help detect plated bars. Poured bars tend to have more surface variations which can affect the readings, so it's best to test on the flattest area available, and to test multiple areas on the bar. Sigma recently released a new accessory for the PMV PRO, a large External Bridge. This is a larger version of the bridge sensors on the main unit that plugs into the DB port on PMV PRO. This sensor is able to read all the way through large bars (roughly kilogram size up to 100 oz) as well as take a surface reading, so it's capable of identifying "drilled and filled" bars along with plated bars.

I would probably use the large wand and test the bar in a lot of different places and see if the readings very much. Just a thought.

@@FakeBullion how much is the larger external bridge?

good question

MSRP on the External Bridge is $485. Some retailers may offer it for less, especially if you are buying it as part of a package deal. You can add an External Bridge to an existing PMV Pro, but you do have to ship the PMV to Sigma to have the External Bridge matched and calibrated.

They are all nominally the same 90% silver, 10% copper alloy. However, older coins tend to have more contaminants in the non-silver 10% balance of the alloy. It only takes a trace amount of lead, tin, or a few parts per million of iron to affect the resistivity. Sigma Metalytics checked hundreds of coins to measure the average range of resistivity values and found it was best to make three groups. The older coins have a wider range of acceptable resistivity values. The newer coins tend to have fewer contaminants, so they have a more narrow range of acceptable resistivity values.

@@MPD90 it ain't passing the drop test

@@MPD90 most people get fooled but for the folks who know what they're looking for dimensions are a dead giveaway

@@09nedly09 Its kinda nuts how many different ways you can check a coin... by weight, dimensions, ultrasound, induction, xrf, chemical, Acoustic(drop or ping test) magnets.....

There is no "digital drop gauge" anywhere in the PMV PRO. The two bridge sensors on the PMV PRO are standard, not "optional" as you claimed in another comment, as they are the main sensors on the base unit. A larger External Bridge is optional for testing larger bars (up to 100 oz silver, 400 oz gold). The PMV PRO is not calculating the density. It works essentially the opposite of your assumption. The PMV PRO assists the user in checking the physical dimensions of the sample without requiring a separate measuring tool (calipers) or calculating the volume by hand, in order to verify that the density of the sample falls within expected values for that metal/alloy. The user selects the metal/alloy they are testing from the menu on the device and enters the weight of the sample. The device contains a database of known resistivity and density values for each metal/alloy it can test. The Bridge Sensor measures the thickness of the metal in the sample (whether a plain coin or encased in a slab) electrically while also measuring surface and through resistivity, and calculates the expected diameter or length/width of the piece based on the known density of that metal/alloy. The user can then check the diameter or width/length of the piece on the screen to see if it falls within the expected range. This method is sufficient to differentiate commonly tested precious metals from the much-less-dense metals (brass, copper, zinc) typically used in counterfeits. Only a few metals (such as tungsten or platinum) are dense enough to match both the weight and size of genuine gold bars/coins, and those metals have higher resistivities, meaning they fail the PMV's resistivity reading. Silver is the most conductive metal, so any metal that could match the density of silver will have a measurably higher resistivity. This is why it is important to always check the size and weight, on top of checking the main resistivity reading on the PMV. A different bulk metal will fall outside the expected range for at least one test or the other. This method works for common round and rectangular coins and bullion that fit under the bridge sensors. The PMV cannot verify the density of other odd shapes or very high relief coins. For those items the user could get a surface reading from the PMV using the optional wands, but would need to use water displacement or some other method of measuring the volume to calculate the density.

Yah, but you will never be able to locate these guys....