Frequently Asked Questions | Goldanalytix
Here you find answers to the most frequently asked questions on all topics related to precious metal testing. The questions and answers are neatly arranged according to key topics - so you can find what you are looking for very quickly.
Ambiguities while testing
In some silver coins (fineness 999) there are "impurities" in the last thousandth in the sense of e.g. iron or nickel, which can be traced back to unclean production methods in the past. The classic coin for this is the Krugerrand silver (conductivity: approx. 55 - 60 MS/m). This means that the coin often slips into the copper range or below on the GoldScreenSensor, although it is real.
Additional measuring methods will confirm the authenticity of the coin.
The same effect can also be seen with other objects such as the silver coin "Tokelau 4th Edition Terra | Earth 2021".
For some new fine gold investment coins (e.g. Kangaroo 2021, Lunnar Series III 2021) the measurements are at the upper end of the spectrum (mostly 46 to 48.5 MS/m). Thus, some coins show too high values, even though they are real. This is probably due to a new type of coating on the coins, which is supposed to protect them from damage. Therefore, if the dimensions and weight are correct, there is no need to worry.
- Be careful when handling the magnet, otherwise it may cause injury.
- There should be no electronic devices in the vicinity, as these can be damaged by the neodymium magnet.
- An electrostatic charge can falsify the measurement result, so make sure to discharge the packaging or the plexiglass structure with the anti-static spray.
- Test the objects for ferromagnetic materials/impurities beforehand with the supplied bar magnet, otherwise the scale may be damaged or the result is incorrect.
- With experience it takes about 30 seconds to take a measurement and calculate the result.
- Make sure that the scale is located as steady and vibration-proof as possible.
- Ideally, start the device 5-10 minutes before you use it so that it can regulate itself.
- The density scale works most reliably in a stable environment with a room temperature of 20-25 °C. The most important thing is that the temperature remains constant during the time of operation or use.
- Also note that you cannot use the density scale to measure jewellery set with precious stones, as stones falsify the density. Also, do not weigh any substances that react with water, e.g. sodium or potassium, or have a water-soluble layer.
- The test specimen must be dry and clean.
- Remove any capsules and blisters before measuring, otherwise the result will be inconclusive.
- With weakly wetting liquids (e.g. normal water), air bubbles may accumulate on the carrier or the test piece. An air bubble with a diameter of 2 mm already causes a measurement inaccuracy of 4 mg.
When measuring, it is important not to measure only at one point, but to always take measurements at several points on the object for the test. In addition, you should take care not to press on the tip of the GoldScreenPen, but only to place it on the object. Otherwise, the GoldScreenPen may measure its own metal tip. In order to obtain an accurate measurement result, the measuring tip must be in full contact with the test specimen and not only in partial contact, otherwise the device will measure air and this can distort the measurement result. With extremely small or small-limbed pieces, no clear result can be delivered.
In addition, it is important to pay attention to the size/thickness of the object, because if the test piece is too large, the GoldScreenPen can no longer identify all forgeries, as the penetration depth could be too shallow. Therefore, please use the GoldScreenPen only for bars and coins up to 1 ounce. In addition, at least one other measuring method should be used (e.g. calipers and precision scales).
When measuring with the BarScreenSensor, it is important to remove the packaging of the object and apply the ultrasound gel to the measuring head. The measuring head must be in direct contact with the test piece.
It is also necessary to scan the entire ingot. It is possible that foreign metal inclusions can only be found at certain points within the object. In addition, the ingot should be physically measured beforehand so that the measured ultrasonic value can be compared with the real thickness.
Furthermore, it is important to pay attention to the size/thickness of the object. If it is too thin, the BarScreenSensor could give wrong results. Therefore, please use the BarScreenSensor only for bars of 50 grams or more. In addition, you should use at least one other measuring method (e.g. digital caliper and precision scale).
The smaller the bar to be tested, the more embossing and stamps in the gold/silver have an effect on the measurement result.
The density scale only indicates the weight of the test piece in the water. To calculate the density, you need the normal weight of the piece and the weight of the object in the water. To free you from having to do your own calculations, we provide you with our Excel calculation tool, which does the maths for you. Simply enter your measured values and the density of your piece is calculated.
If you get a positive result from the magnetic balance, then the material at hand is diamagnetic. If the result is weakly negative, then it is paramagnetic and if it is strongly negative, then the object is probably ferromagnetic. In most cases, a negative result means that the test piece is not a pure precious metal. However, there are some exceptions to consider: e.g. older Krugerrand coins.