Diamonds are valued for their hardness. They can last for generations in jewelry and are resistant to scratches from daily use. Like knives or drills, they can be plunged into almost anything without breaking. Powdered diamonds polish precious stones, metals and other materials.

So is there anything harder than diamond? The answer turned out to be a little difficult to find.

According to Richard Keiner, a materials chemist at the University of California at Los Angeles, in most practical terms diamond is still the hardest material. There are ways to create diamonds that are harder than ordinary gemstones. There are other materials that could theoretically be harder than diamond, but they do not exist in a form that can be held in the hand or used widely.

While anyone who has worn a diamond ring can attest to the crystal’s durability, it’s important to understand that “hardness” means something very specific to scientists, says geochemist Paul Asimov of the Cal Institute of Technology. It is often confused with other qualities such as hardness or durability. These factors are sometimes, but not always, associated with stiffness.

For example, a diamond is very hard, but only moderately hard. And it’s surprisingly easy to break: It crumbles easily at the edges of the crystal; This is how gem cutters can create beautiful, versatile diamonds that sparkle.

Scientists measure hardness in several different ways. Geologists often rely on a comparative measurement called the Mohs hardness scale, which is a way to identify minerals in the field by whether they can scratch each other. The diamond has a highest grade of 10, which means it can scratch almost anything. Soft loose talc – 1.

In the laboratory, materials scientists rely on a more precise measurement called the Vickers hardness test, which determines the hardness of a material based on the force required to indent it with a pointed tip. (To visualize this, imagine sticking a pencil to a rubber band.)

A diamond consists of carbon atoms arranged in a cubic lattice, held together by short, strong chemical bonds. This structure gives it its famous hardness. Most materials claimed to be harder than diamond are obtained by slightly altering the classical crystal structure of diamond or by replacing some carbon atoms with atoms such as boron or nitrogen.

The main competitor for a material harder than diamond is lonsdaleite. Like diamond, lonsdaleite is composed of carbon atoms, but they have a hexagonal crystal structure rather than cubic.

“Lonsdaleite is very mysterious,” Asimov told Live Science. Until recently, it was mostly found in meteorites in such small quantities that it was unclear whether to consider it as a separate material or a defect in the standard crystal structure of diamond.

Recently, a team of scientists discovered micron-sized lonsdaleite crystals in meteorites; these are still small crystals, but much larger than previous finds. According to Asimow, this gave the mineral greater credibility. Other scientists have reported lonsdaleite forming in the laboratory, although the crystals only existed for a few seconds.

So lonsdaleite is interesting but will not be able to replace diamond in applications such as cutting, drilling or polishing in the near future.

By playing with the nanostructure of diamond, you can also obtain a material that is harder than normal diamond. A material composed of many small diamond crystals will be harder than a single-crystal gem-grade diamond because the nano-sized grains are interlocked rather than passing each other. Diamond “nanopairs,” in which the grains form mirror images of each other, are reportedly twice as hard as regular diamonds.

But at the end of the day, most scientists aren’t just looking for superhard materials to break records, they’re also trying to create something useful.

“Materials scientists spend a lot of time inventing superhard materials that can be produced on a large scale,” Asimow said. “And in most cases being harder than diamond is not a design criterion.” Scientists may want something almost as hard as diamond, but cheaper or easier to make in the laboratory.

For example, Kaner’s laboratory has produced many superhard metals that can be used in industry instead of diamonds. Currently commercially available, it is a combination of tungsten and boron with some other metals added. The shape of the crystals gives the material different properties in different directions; hence, if held in the right direction, it can scratch the diamond. Keiner told LiveScience. It is also more affordable to create, in part because it does not require the high-pressure conditions used to make diamonds in the laboratory, he noted.

So while diamond in its many forms still leads the way in terms of hardness, the classic material will face challenges to its throne in the future. Source