In recent times, the case of a jeweler capable of recognize gold simply sniffing it. But there is really one scientific base Behind this statement? The answer is yes: it’s all a matter of chemistry. In short: if the object taken into consideration stinks of “metal” (then we will understand which odorous molecules are behind), it is not gold. If, on the other hand, these smells do not give off, it is a good chance of gold. Anyway this is only a quality method. To be certain, further chemical-physical tests that we deepen in this video-article are needed.
Because if we touch a metal object, it stinks “metal”
If you have ever touched coins of copperfrom the keys or any object in ironyou will have noticed that the hands They remain with a characteristic “metal” smell. But what happens on a chemical level? In reality, ours nose does not perceive the metal same: they are not here Metal atoms that evaporate and enter the nose. What happens is that i fat of the skin react with iron or copper transforming into odorous molecules. Among these, the main person in charge ofmetallic smell It is the 1-Otten-3-Onea molecule derived from the reductive degradation of lipid peroxides. At the bottom of the article find the study.
Because gold has no smell and does not “stink”
Gold is a metal noblewhich means that it is extremely stable and does not react easily with the surrounding environment. Unlike iron or copper, gold does not interact with skin fats to form odorous molecules. In simple words: thegold does not smell of metal.
So, if a jewel gives off a metal smell when it rubs it in your hands, it is very likely that it contains less noble metals such as iron, copper or zinc. If instead it is odorcould actually be authentic gold.
The methods used to recognize gold
Obviously, smelling gold is only a first qualitative test. For more in -depth verification there are other scientific techniques:
- Test with nitric acid: gold does not melt in nitric acid, while the less noble metals yes. In the video we deepen the chemical composition of the different mixtures used to take the tests.
- X -ray pistol (XRF): This tool, also called portable XRF analyzer, analyzes the fluorescence emitted by metals to determine its composition.
- Magnet method: If an object is attracted, it is not formed with gold. This is because gold is not a ferromagnetic material and therefore is not attracted.
We remember in any case that the jewels often present a small engraving which indicates the purity of gold. For example if there is the writing 750means it’s gold 18 carat. Here is an indicative table of the most common caratures, with the relative percentage of gold (rounded) and the corresponding title in thousandths:
- 24 carats (24k): ~ 99.9% pure gold (999/1000)
- 22 carats (22k): ~ 91.6% pure gold (916/1000)
- 21 carats (21k): ~ 87.5% pure gold (875/1000)
- 18 carats (18k): 75% pure gold (750/1000)
- 14 carats (14k): 58.5% pure gold (585/1000)
- 10 carats (10k): 41.7% pure gold (417/1000)
- 9 carats (9k): 37.5% pure gold (375/1000)
