38. Can you counterfeit gold with tungsten?
Tungsten is the only metal that has similar properties to gold, so counterfeiting is not unthinkable. An important similarity between gold and tungsten is that the specific gravity is almost the same. To illustrate, a liter of gold has a weight of 19,320 grams and tungsten a weight of 19,300. However, there are important differences between these metals in color, hardness and melting points.
What is Tungsten?:
Tungsten is a transition metal. A well-known application of tungsten is the use of filament in halogen and incandescent bulbs. In addition, tungsten is used to harden materials or make them more heat-resistant. An example of this is its use for armor steel and bullets. Tungsten is also used for bulletproof glass, as the coefficient of expansion is the same (i.e. it expands immediately when heated). A common name for tungsten is tungsten. Tungsten is in the 18e century. In 1783, tungsten was worked as metal for the first time. Beginning 19e century, tungsten was first used in incandescent light bulbs.
| Comparison properties: | ||
|---|---|---|
| Gold | Tungsten | |
| Density (grams/dm3) | A 19,320 | 19.300 |
| Melting point (°C) | 1.064 | 3.422 |
| Hardness (MOHS - scale 1-10) | 2.5 | 7.5 |
| Color | Yellow | Grey-white |
Tungsten has an extremely high melting point of 3422 °C, making it the highest melting point of all metals. The hardness of tungsten is significantly more than gold. Especially combined with the high melting point, tungsten remains hard at higher temperatures. The color of tungsten is grayish-white. This is not a unique color in metals and is a distinct difference from the yellowish color of gold.
Counterfeit gold bar:
Because tungsten and gold have almost the same density, it is said that tungsten is the ideal product for Gold bars to be falsified. There are a number of differences between gold and tungsten that need to be bridged. This mainly concerns the color difference and the hardness. The color difference can easily be solved by a small layer of gold around it. More gold is needed for hardness. This also applies to allow the bar to pass a surface test. It is expected that more than 6% gold is needed to make the forged bar credible. This already makes such a forgery somewhat expensive, but of course it remains considerably less than a pure gold bar.
Testing for authenticity:
The use of gold in a tungsten bar means that a test for authenticity is not easy. A surface test would not be sufficient. It is important to know how we can test the authenticity of these bars. The most rigorous solution is to melt the bar and analyze it. However, there are alternatives, albeit less reliable. A practical test is to drive a nail through the bier. The nail can easily penetrate fine gold and tungsten, but not tungsten, or with considerably more resistance. An alternative to keep the gold bar undamaged is a sound test. Metal can be tapped against the gold bar and also against a gold bar that is definitely real. Due to the harshness of tungsten, a difference in sound may be audible here.
At the end of 2009, there was turmoil in the market when China came out with the report about counterfeit gold bars . According to this report, some of the bars supplied from the United States were partly tungsten. From the serial numbers it could be deduced that these gold bars came from Fort Knox. Critics questioned the authenticity of the gold bars stored at Fort Knox.
