How hard are jewelry stones?

How resistant are the stones of your jewels? Can they be damaged easily?

The hardness of gems is measured by the Mohs scale. The name derives from the German scientist Friedrich Mohs, who conceived it in 1812. The Mohs scale assigns a grade from one to ten to the degree of hardness of the stones. In this way, you can know which ones are more delicate, for example, which scratch or break more often. It is an aspect that is best known to avoid nasty surprises: knowing how hard the stones of your jewels are is also useful for cleaning. For example, an opal is not as strong as a ruby ​​and should be treated with greater delicacy.

Gemme di Filippo G&G
Gemme di Filippo G&G

In short, generally when someone buys a piece of jewelry they don’t ask you if it will be tough enough to withstand occasional bumps. Yet it is a question that is best to ask yourself, especially if the stone is mounted on a ring, a jewel that is more easily subject to contact with other materials. But the same goes for earrings or necklace if these jewels have stones.
Diamante taglio cuscino di Jack Reiss. Il diamante è l'elemento più duro in natura
Diamante taglio cuscino di Jack Reiss. Il diamante è l’elemento più duro in natura

Although we tend to believe that a stone is incredibly more solid than any common object of everyday life, this is not the case. The gems of your jewelry could be fragile stones, at risk of being scratched or even shattered in some unfortunate circumstance. Even the diamond is absolutely not safe from all danger. Fortunately, Mohs took the trouble, almost two centuries ago, to measure the hardness of different minerals, including precious stones. It is therefore possible to know the degree of hardness of the stones with some certainty.
Granato demantoide7-7,5
Granato6,5 - 7,5
Corallo fossile6,5-7
Spessartite6,5 - 7,5
Occhio di tigre6,5-7
Zircone6,5 - 7,5
Tsavorite6,5 - 7,5
Rhodolite6,5 - 7,5
Sillimanite6,5 - 7,5
Labradorite6 - 6.5
Pietra Luna6 - 6.5
Giadeite, giada nefrite6 - 6.5
Amazzonite6 - 6.5
Opale5.5 - 6.5
Ematite5.5 - 6.5
ChrysocollaDi 2 - 4

The Mohs scale was initially based on ten readily available minerals. This ranking was subsequently completed and is now an important indicator for those who buy a stone. But be careful: it is a special scale. For example, a corundum (such as ruby) is twice as hard as a topaz, but a diamond is nearly four times harder than a corundum. What you see on this page is a table that summarizes the hardness of the main stones. At the head is the diamond. Immediately after there are rubies and sapphires. Then … Federico Graglia
Acquamarina e tormalina rosa di Nomads
Acquamarina e tormalina rosa di Nomads

Set di spinelli di diverse sfumature di Paul Wild
Set con spinelli di diverse sfumature di Paul Wild

That’s how tough your diamond

You want to know how tough is your diamond? In this video, a diamond is crushed by a hydraulic press. Look what happens.
How tough is the diamond of your ring? You run the risk of scratching or even it breaks? And if it went against something very solid? As you know, the diamond is the more tough element in the world. But this does not mean that it can withstand anything. Precisely: what is its level of resistance? There is who tried.

In this video you can see the outcome of the test: a 0.25 carat certified diamond Gia, worth about 2000 Euros, was crushed by a hydraulic press. The video has attracted more than 11.3 million views. It is not the first experiment with precious materials of Hydraulic Press channel: it has experienced the compression of a black diamond (graphite), a gold Rolex, of an ingot, as well as various other objects, from the iPhone to a sandwich of MacDonald. And the diamond? He Is’ gets along pretty well until…

La scala di Mohs, che misura il grado di durezza degli elementi: il diamante è al top
La scala di Mohs, che misura il grado di durezza degli elementi: il diamante è al top

Anello con diamante da 30 carati
Anello con diamante da 30 carati

Why are they called diamonds (and 21 more surprising news)


Diamonds, the most known and loved gemstone, hides many secrets: here are 22 of them you need to know ♦ ︎

You know that diamond is the hardest material that exists and it is forever. You also know what the 4 C’s are (and if you don’t know it read here). And you also know that diamonds can also be colored. But there are 22 other amazing aspects of the diamond that you need to know.

Diamante taglio cuscino di Great Diam
Diamante taglio cuscino di Great Diam

1 Do you know why diamonds are called that? The name derives from the ancient Greek word ἀδάμας (adámas), which means unalterable, indestructible, untamed.
2 How long has humanity been searching for and wearing diamonds? According to anthropologists, diamonds were recognized and extracted for the first time in India, between 600 and 300 years ago. Diamonds were found in alluvial deposits along the rivers Penner, Krishna and Godavari.
3 It is well known that the diamond has the maximum hardness. Less known that it also has a high thermal conductivity, that is the aptitude to transmit heat. This is also why diamonds are used in many industrial applications such as cutting and polishing tools.

Ricerca di gemme in miniera
Ricerca di gemme in miniera

4 If you can, bring your ear close to a diamond and listen. Well, you need a diamond of a certain size, but know that through this gem the sound passes at the highest speed.
5 Even if diamonds are heat transmission, the gems also has a high electrical resistance. You don’t get thunderstruck through a diamond.
6 Diamonds are hard, but can scratch other diamonds. And this can cause damage to one or both stones. When storing them, make sure that the stones do not collide.

Esame di un diamante a un precedente Dubai Jewellery Show
Esame di un diamante durante Dubai Jewellery Show

7 Another interesting property of diamond: it is chemically inert, ie it does not react with most corrosive substances and also has excellent biological compatibility. No diamond allergy is known (thankfully).
8 Colored diamonds are determined by small defects or impurities inside them. In particular, when the diamond is blue it means that inside it has boron, yellow or brown nitrogen atoms, if it is green it is because it has been exposed to radiation, such as violet, pink, orange or red.
9 Nitrogen, responsible for the yellow and brown color, is by far the most common impurity found in diamonds.

Anello della collezione Cannella, in oro rosa e diamanti brown
Brusi, anello della collezione Cannella, in oro rosa e diamanti brown

10 The diamond also has a high optical dispersion (ability to disperse light of different colors) and for this reason it is so bright.
11 How old are diamonds? Much: most natural diamonds are between 1 billion and 3.5 billion years old.
12 Where do diamonds come from? From the belly of the Earth. Most were formed at depths of between 150 and 250 kilometers in the earth’s mantle and some as deep as 800 kilometers. But today they are found at lower depths, because they have been brought to the surface by volcanic eruptions and deposited in rocks known as kimberlite and lamproiti.

Anello con diamante taglio rotondo di circa 13,70 carati firmato Bulgari
Anello con diamante taglio rotondo di circa 13,70 carati firmato Bulgari

13 You will have heard that diamonds are, in practice, compressed coal. But it’s false. Coal is a material formed from prehistoric buried plants, while most diamonds are much older than the first terrestrial plants. However, it is possible that diamonds can be formed from coal in some particular areas, but the diamonds thus formed are very rare.
14 Would you like to have so many diamonds? Then go into space. Although diamonds on Earth are rare, they are very common in meteorites: about 3% of the carbon found is in the form of nanodiamonds, only a few nanometers (one millionth of a millimeter) large. But, according to astronomers, some extrasolar planets could be almost entirely composed of diamonds.
15 The diamond trade is very concentrated: around 90% of the world’s diamonds are cut and polished in Surat, India.

Anello con diamante fancy yellow
Anello con diamante fancy yellow

16 The most precious stones are cut in Antwerp’s cutting and trading centers in Belgium, where the International Gemological Institute is based, in London, in the diamond district in New York, at the Diamond Exchange District of Tel Aviv and Amsterdam.
17 When cutting a rough diamond the weight reduction can be in the order of 50%.
18 Cut a diamond is not easy: the stone can be divided by a single well calculated shot, with a hammer and a pointed instrument. But it is a very risky system. In practice, a precision diamond saw is usually used, which is a more reliable but long system.

Il diamante Lesotho Pink grezzo
Il diamante Lesotho Pink grezzo

19 Colored diamonds are in fashion. But only a few years ago: those browns were a large part of diamond production, but they were used mainly for industrial purposes.
20 Brown diamonds were once not valued on the diamond color scale. But after the development of the Argyle diamond mine in Australia, in 1986, they were considered acceptable gems and used in jewelry.

Selezione dei diamanti nel laboratorio di Antwerp (Anversa)
Selezione dei diamanti nel laboratorio Tiffany di Antwerp (Anversa)

21 The Argyle mine in Australia, with its 35,000,000 carats (7,000 kg) of diamonds per year, produces about a third of global production of natural diamonds. And 80% of Argyle diamonds are brown.
22 What was the biggest diamond theft? It took place in February 2013 at Brussels airport. The thieves fled with gems worth an estimated 50 million dollars. But later the gang was arrested and some of the diamonds were recovered.

Il diamante The Mirror of Paradise, 52,58 carati, D Color, IF, venduto per 6,5 milioni
Il diamante The Mirror of Paradise, 52,58 carati, D Color, IF, venduto per 6,5 milioni