TOP 10 Strongest Gemstones: Zero (or Almost Zero) Risk of Breakage!

We all have a fear: buying a necklace, a ring or even a sculpture, and then PAF, the extra shock. A split or cracked stone, a broken piece of jewelry, but above all, a stone millions of years old shattered (and our bank account lighter).

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And in those moments, after going through the 5 stages of grief, you wonder what could have happened! After all, diamonds are invincible, beryls are forces of nature! Unbreakable topazes!

Well, yes, but no. Because we’re quick to forget a key distinction in the debate: toughness and tenacity are two different things! So how are the strongest gemstones made?

It’s common to mix up the two concepts, thinking that a stone that scores a perfect 10 on the Mohs scale, like the precious diamond, is invincible. This belief is reinforced by depictions in films, where thieves and heroes use diamond points to open windows. In reality, it simply illustrates the principle of hardness.

Toughness vs. Hardness: The explanation

In a nutshell: hardness is a material’s resistance to scratching and abrasion, while toughness is its resistance to impact and breakage. A stone may therefore scratch more easily but be almost unbreakable, whereas a stone that is impossible to scratch may be easy to break. Yes, it takes the head, doesn’t it?

Hardness and geological formation are linked

Generally speaking, stones that have been subjected to intense pressure and formed deep in the earth are harder and more resistant to scratching. This is why diamonds, rubies and topaz that form at depth are much harder than turquoise or feldspar that form on the surface. This difference in hardness is mainly due to the pressure exerted during their formation. For example, carbon, which makes up the entirety of diamonds, is more fragile and soft on the surface, but becomes extremely hard when formed deep in the Earth.

Toughness and internal structure of stone are linked

By contrast, toughness, which measures a stone’s ability to resist impact, depends less on its depth of formation (although this can be a factor) and more on its crystal structure.

To illustrate this, imagine a door with seven locks, all closed. A blow to one corner will open all the locks in its path.

• If the door has no lock…it opens with a simple push. These are amorphous and organic materials. No internal crystal structure and therefore no lock. They can split in any direction, as in the case of opal and coral, for example.
• If all the locks are aligned, one shot will open all the locks at once and the door will open. These are crystalline stones with what is known in the trade as perfect cleavage. The stone has several rows of locks running parallel to each other: a shock at this angle will open all the locks and split the stone perfectly in two, no matter how hard it is. Such is the case with fluorite.
• If the locks are distributed in 2 or 3 different places on the door, a blow at the right angle will only open a handful of locks, leaving at least half of them closed. It will be possible to open the door, but this will require forcing the remaining locks with heavy blows. Easier to open than numerous, random locks, less easy to open than aligned locks, these stones will generally be resistant with a weakness if shocked into a precise angle. This is true of most stones.
• In the case of locks randomly distributed on the door, a single blow is unlikely to open any or very few locks. The door won’t budge except in the event of very heavy impact (imagine the police forcing open a door with a battering ram). These are polycrystalline stones.
  They are made up of thousands of microcrystals in all directions, sometimes of different varieties, making it impossible for all these microcrystals to be oriented in the same direction. The stone will therefore be tough and shock-resistant. Such is the case with agate and jade.

Hardness and Inclusions: the two other criteria to consider

Of course, hardness plays an important role, as a soft stone will crumble on its own, without the need for splitting… This is the case for gypsum and talc.

Now that we understand the natural toughness of a stone, let’s talk about inclusions! A stone can be highly resistant to scratches, have good toughness but break easily…because inclusions in a stone carry a risk: they create “holes” in the structure of the stone and therefore a weakness.

Imagine you’re in a perfectly balanced tug-of-war and suddenly one of your teammates disappears or is transformed into a giant gas bubble? Good luck keeping the balance with your opponents.

That’s what happens with Emerald or Feldspar! These stones are so full of inclusions that they are brittle, despite their rather decent natural hardness and toughness (if the inclusions were removed). That’s why a synthetic emerald is so much more resistant than a natural emerald: because it won’t have any inclusions!

Top 10 Most Solid Gemstones: The Ranking!

Now that you have a clearer picture (or if you’ve skipped right over the scientific blah, blah, blah), I’ve concocted a top 10 list of the most solid gemstones, i.e. those that present THE LEAST risk of breakage on impact.

Here we go!

N°1: Jade jadeite – The unbeatable…but not in water

Extremely popular in China in its translucent pure-green imperial variety, the famous jade jadeite is the world’s most enduring stone. It’s so shock-resistant that the Chinese Empire used it as an anvil ! Need I say more? Unfortunately, good quality jade is not so easy to find, and you have to watch out for internal fractures and bleaching treatments that weaken its structure. With a hardness of 7, it is scratch-resistant, but beware of lakes, pools and seas, as jade is sensitive to water.

N°2: Nephrite jade – Waterproof…but still not waterproof

Slightly less tenacious than its cousin jade jadeite, notably because of its lower hardness, nephrite jade remains in the top rankings with superb tenacity and a reasonable hardness of 6.5. As with jadeite, nephrite jade can be bleached or fractured. It is also sensitive to abundant water!

No.3: Polycrystalline quartz – A wide, versatile and affordable range

Chalcedonies such as cornelias, sardines, prases, chrysoprases, agates and onyxes, as well as jasper varieties , fossil woods, tiger’s eye and aventurine are all covered by this designation! By their very nature, they will be highly resistant to breakage, rather affordable and still impressive in the face of scratches thanks to a hardness of 6. Now you know why we make quartz worktops and why you shouldn’t be afraid to sit on them (if they’re thick enough, of course)!

N°4: Lapis lazuli – The ornamental gemstone

This may seem odd when you consider that lapis only has a limited hardness only 5.5 and is sensitive to chemicals, however, lapis lazuli has a high surprising tenacity ! Due in large part to its polycrystalline rock structure (different crystals mixed together), it is very difficult to break a lapis ! It’s more likely to be scratched or abraded.

N°5: Moissanite – The all-round winner

The eternal diamond competitor, synthetic moissanite is a laboratory-created moissanite. With very high toughness and a hardness of 9.3, it outperforms corundum and is also highly water-resistant, so you can take it to the sea if you like! She loses the tenacity match, but wins the all-category durability contest hands down!

N°6: Chrysoberyl – Tough, tenacious and pool-ready!

Chrysoberyl and its Alexandrite variety are among the toughest and most durable gems. With a hardness of 8.5 and excellent resistance to acids and chemicals, it’s a stone that can generally be worn even in the swimming pool!

N°7: Alexandrite – The best optical effect

Of course, being a color-change variety of Chrysoberyl, alexandrite is perfectly suited to impact and also benefits from the hardness of 8.5, making it a surprisingly durable gem.

N°8: Le Saphir – Silver medal in all categories

Sapphire is the second hardest stone in this ranking, with a hardness of 9 and remarkable toughness! Shock- and scratch-resistant, with little sensitivity to acids and chemicals, it is an extremely durable stone. The synthetic version is just as important, if not more so, as it will be devoid of inclusions and therefore of the risk of internal fractures.

N°9: The ruby – Joint silver medal in all categories

Of course… just like sapphire, ruby is a remarkably tough corundum with a rock-solid hardness of 9, beaten only by diamond and moissanite!

N°10: Spinel – Honorable mention!

Although spinel shares its crystal system with diamond, it is remarkably tenacious and generally refuses to split. With its hardness of 8 and water resistance, it has well earned its place in this ranking!

So, would you have said the same?

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