Distinguishing real gold from imitations or less valuable alloys can be difficult without the proper knowledge and the right equipment. One of the lesser known methods, and only in some cases effective, is to use the sense of smell.
Pure gold is a noble metal that does not react with the environment or with substances present on human skin, resulting in odorlessness. On the contrary, many metals used in alloys or imitations can emit the typical “metal smell” following chemical reactions with sweat, grease and dirt.
Pure gold (24 carats) is a noble metal that does not oxidize or react with oxygen or moisture in the air. This chemical stability is what makes it resistant to corrosion and oxidation, maintaining its shiny appearance over time. Its chemical inertia is also the reason why it does not give off any odor.
When handling pure gold, you will not perceive any metallic odor because there is no reaction between the metal and substances present on the skin, such as sweat, grease or dirt. This clearly distinguishes it from other metals that, instead, are more reactive and can develop volatile compounds that emit perceptible odors.
Furthermore, pure gold has an extremely stable atomic structure that prevents the formation of volatile compounds during contact with external agents. This characteristic is one of the main reasons why gold has been chosen over the centuries for the creation of valuable jewelry and coins.
Even environmental conditions do not affect pure gold: high temperatures, humidity or exposure to sunlight do not cause any significant chemical changes that could generate odors. However, when gold is alloyed with other metals, such as copper or silver, the situation can change dramatically. These metals, in fact, react easily with the surrounding environment, contributing to the formation of the typical metallic odor.
The total absence of odor is therefore one of the most reliable signs to recognize pure gold. However, it is important to remember that even small quantities of other metals present in the alloy can influence this characteristic.
#2. Reactions between metals and skin
Human skin is naturally covered with a layer of sebum, sweat, and other organic substances. Some metals, such as copper, iron, or silver, react easily with these compounds. For example, copper can oxidize to form cuprous oxide, while iron can develop traces of rust when exposed to moisture.
These reactions lead to the formation of volatile compounds that easily bind to the molecules of grease and dirt present on the skin, generating the characteristic metallic odor. This is why, after handling coins, keys or metal objects, the hands may have a persistent metal odor.
In particular, sweat contains mineral salts and acids that can react with reactive metals. The sodium chloride present in sweat, for example, can accelerate the oxidation processes of iron and copper, favoring the production of volatile molecules responsible for odor.
Silver , while less reactive than copper and iron, can still oxidize in the presence of sulfur, forming silver sulfide, which also contributes to the metallic odor. Additionally, silver can react with organic compounds on the skin, generating additional volatile products.
On the contrary, pure gold does not participate in these chemical reactions. Its chemical inertia makes it immune to oxidation and the formation of odorous compounds, ensuring a total absence of odor even after prolonged contact with the skin.
#3. The typical smell of metal
The odor we commonly associate with metal is not emitted directly by the metal itself, but is the result of chemical reactions between the metal and human skin. When sweaty or slightly dirty hands come into contact with metals such as copper or iron, small amounts of volatile organometallic compounds are generated.
One such compound is 1-octen-3-one, a molecule that has a strong, pungent odor and is formed when skin oils react with trace amounts of reactive metals. This explains why some jewelry or metal objects leave a distinctive odor on your hands after prolonged handling.
Other compounds responsible for metallic odor include aldehydes and ketones formed by the reaction between fatty acids on the skin and metals. These compounds have pungent, persistent odors that can be easily detected even at low concentrations.
Pure gold, on the other hand, being chemically inert, does not participate in these reactions, remaining odorless even after prolonged contact. However, when gold is alloyed with other metals, such as copper or silver, chemical reactions can still occur, producing perceptible odors.
This characteristic makes the sense of smell a useful tool for distinguishing pure gold from less noble alloys or metals, especially in situations where professional analysis tools are not available.
#4. Techniques to recognize fakes
To recognize if an object is actually gold using your sense of smell, just follow a few simple steps:
Clean your hands: Make sure your hands are clean but not completely dry, as a slight presence of sweat promotes the reaction.
Rub the object between your fingers: Hold the object in your hand and rub it gently for a few seconds.
Smell your fingers: If you smell the typical metallic odor, it is likely that the object contains metals other than pure gold.
This method is particularly useful for identifying low-gold alloys or plated objects that use reactive metals beneath a thin gold surface.
However, it is important to consider that some gold objects may contain small percentages of other metals to increase their resistance and durability. In these cases, the odor may be slightly perceptible but much less intense than that emitted by non-noble alloys.ggermente percepibile ma molto meno intenso rispetto a quello emesso da leghe non nobili.
#5. The role of gold purity
Investment gold is defined by Italian law as gold in the form of ingots or plates with a purity equal to or greater than 995 thousandths, and gold coins with a purity equal to or greater than 900 thousandths, minted after 1800 and which are or have been legal tender in the country of origin.
Investment gold coins with a fineness of around 900 thousandths (90% purity or 21.6 carats) contain a significant amount of gold, which is odorless. However, the presence of 10% of other metals, such as copper, could in some cases contribute to a slight metallic odor, especially if the percentage of non-noble metals is sufficient to trigger reactions with substances present on the skin.
The high percentage of gold in investment coins significantly reduces the likelihood of detecting a metallic odor, but does not eliminate it completely. In general, the higher the purity of gold, the less likely it is that you will detect odors due to chemical reactions.
This characteristic makes investment gold more reliable than other gold alloys on the market. However, it is always advisable to use multiple verification methods to ensure the authenticity of gold, especially when it comes to purchases of significant value.
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