Can Diamond Break: The Physical Properties of Diamonds

Diamond is actually a crystal-like mineral composed of the element carbon. Except for diamonds, which consist of only one element, all precious stones are formed by the combination of several different elements. Diamonds contain very well-structured and arranged atomic particles, and they crystallize in a cubic or isometric system. This crystal structure of diamond gives it incredible hardness. The hardness is the most important factor affecting whether diamonds can break or not. So, can diamonds break?

Diamonds can break, yes. However, it is incredibly hard to break a diamond. The crystal structure, hardness, and other physical, as well as chemical properties of diamond, make it so hard to break. It is extremely out of the ordinary for a diamond to break. Today, with the developing technology, compounds and alloys that can break the diamond can be produced, albeit rarely. Let’s take a look at the properties of the diamond that make it so difficult to break.

Hardness of Diamonds: They Cannot Break Easily

The main reason why diamond is so hard to break is its hardness. In gemology, hardness is defined by a mineral’s resistance to scratching and wear. Diamond, the hardest of all substances in nature, is composed of crystalline carbon similar to graphite, one of the softest minerals known in chemistry. The reason why these two minerals, which are composed of the same substance, are so different in terms of their properties, is the arrangement of the atoms. The atoms of graphite are arranged in hexagonal planes, but the atoms of diamond are tightly bound together in a cubic arrangement.

Although diamond is the hardest of all-natural substances, it is not indestructible. The carbon atoms are more widely spaced in the planes than the others. The worldwide accepted standard for degrees of hardness is known as the Mohs scale. The Mohs scale is based on the strength of one mineral to scratch another. It is a relative scale; It determines the hardness of one mineral relative to another. There is no exact quantitative correlation between the numbers of the Mohs scale, they simply display the scratch hardness in a comparative order. The Mohs scale is as follows:

Diamond 10 (scratches every mineral)
Corundum 9
Topaz 8
Quartz 7 (the higher digit scratches each lower digit)
Orthoclase Feldspar 6
Apatite 5
Fluorite 4
Calcite 3
Gypsum 2
Talc 1 (will not scratch any minerals)

The researchers determined that the diamond is 140 times harder than the closest hardness, corundum. According to diamond cutters, diamonds from some countries may be harder or softer than others.

On the Mohs scale, the number 7 is significant. Indicates the limit for the gemstone. A gemstone must be hard enough to withstand the movement of the gravel with sand particles in it. This is quartz. Opal, pearl, coral, amber, and demantoid garnet do not have this standard hardness and are therefore more preferred for brooches than rings. Hardness testing should not be done on a polished stone as it may damage it.

Physical Properties of Diamond and Their Effects on Breaking

The physical properties and qualities of diamonds are undoubtedly the most remarkable and the most unusual in the world of gemstones. Compared to other minerals, the density of diamond is quite high. To this day, no substance harder than diamond has been found. This hardness prevents the diamond from being broken by another substance. The way diamond reflects light and refracts it into different colors of the spectrum is extraordinary. Another characteristic feature of the diamond is its ability to adhere to oil. If oil is found on the diamond, it reduces the beauty of the stone. Therefore, a jeweler should advise clients to keep their diamonds as clean as possible.

There are two important factors for jewelers regarding the effect of heat on diamonds. The first relates to the heating of the diamonds under the blaster during the repair. Black spots may appear on the surface of the diamond, but these black spots can be easily removed by re-polishing the diamonds without losing more than the weight of the diamond. Rapid cooling and heating a diamond is the second factor the jeweler should know. This factor can also lead to the growth of imperfections inside the diamond. In other words, it can increase the internal cracks and fractures that already exist in the Diamond. Therefore, care should be taken in cases where sudden temperature changes are needed.

Chemical composition

Analysis of colorless diamonds revealed that 99.95% to 99.98% of diamonds are carbon. Special tests have also shown that the remaining 0.02% to 0.05% consists of 30 different elements in very small proportions.

Unbreakability

Unbreakability indicates the resistance of a diamond to impact and breakage. This depends on the strength of the atoms in a substance to stick together. Other terms that can be used are commitment and persistence.

Slit

The slit in a diamond indicates how prone it is to break or split parallel to certain directions. The directions in which cleavage will occur are called slit planes. Every material is made up of small particles or atoms. These atoms are held together by a force of attraction called cohesion. When a certain material is broken, it is understood that the force that causes the fracture is superior to the attraction that holds it together. Thus, the stronger the cohesion, the harder the material will be to break, meaning a greater force than cohesion will be required to break that material.

Slits are caused because the attraction between different planes of atoms is not the same. A diamond can be split into any of the planes parallel to the octahedron faces. Because an octahedron has 8 faces consisting of four pairs of parallel faces, a diamond can split in four different directions. Despite their hardness, diamonds have four weak directions. The strongest is an octahedron parallel to the face. The weakest is the one parallel to the cube. The diamond cutter chooses one of three directions parallel to the cube faces to cut the raw diamond. In addition, this direction will be the most suitable direction to be chosen in order not to lose weight from the diamond.

Cracking

When a diamond receives a hard blow from its tip, it can crack in any direction not parallel to the atomic planes. This is an illegal crack, and the crack can occur in any direction that is out of line. The crack in a diamond often merges with the cleft in one place, creating a splinter-like appearance with a splintery surface.

Durability

There are two factors that determine the durability of a gemstone, its hardness, and unbreakability. A stone may be as unbreakable as jade, but easily scratched, or as hard as topaz, but will be weak to the point of unbreakability because it is prone to splitting.

Electrical conductivity

Diamond is not considered a conductive material due to its high resistance to electricity. In general, the higher the quality (pure, colorless stones), the less conductivity it will have. Only the very rare Type II b diamond, whose natural color is blue, is considered a semiconductor. The ability of Type II b diamonds to conduct electricity contributed to the discovery of very small amounts of boron.

Melting point

The diamond will theoretically melt at a temperature of 3700 degrees (+-100C) if heated in an oxidizing atmosphere and other conditions such as pressure are kept under control to protect it from burning. But to the best of our knowledge, no experiment so far has been successful.

Does the Density of a Diamond Affect Its Breaking

Density does not directly affect if a diamond can break or not, but it has indirect effects. If a person weighs two stones of the same size but of different species (for example, diamond and quartz), they will find that they do not weigh the same. To put it another way, if a person takes a diamond and quartz of the same weight, they will find that they are not the same size. This is because the stones have different densities. More specifically, the density of a diamond is greater than that of quartz. This density of diamonds is thought to be caused by the tightness and density of the atoms present in the stone. It is defined as a mass of matter for each unit of its volume.

Each type of gemstone has a different density. In gemology, this property is expressed as specific gravity (S.G.). Therefore, determining the specific weight of a gemstone is a tool used to identify that gemstone. Gemologists use this test to distinguish between real diamonds and fakes and gemstones. The specific gravity of a diamond can vary from 3.40 to 3.52. Impure industrial-grade diamonds may have low specific gravity, but gem-grade diamonds can have a specific gravity of about 3.52 +-0.01 to 0.01 due to their high degree of purity.

The specific gravity of a stone can be determined using the following formula. The weight of stones in water will be less than their weight in the air. We can get the volume of water by subtracting the weight of the stones in the air from the weight in the water. Then, the result is divided by the weight of the stone in the air. Thus, we can learn the specific gravity of stones. Specific gravity (S.G.) = Weight in air / (Weight in air – Weight in water). Density is expressed in grams per cubic centimeter (g/cm 3). There are two methods for determining the specific gravity of diamonds and their fakes: the hydrostatic method and the heavy water method.

Measuring specific gravity with hydrostatic balance

The stone is first weighed in air. Then, with the help of tweezers, the wire is placed in a basket and immersed in water. The stone is measured again in the water. The sliding door must be closed and care must be taken to keep the scale-free from vibration. When balance is achieved, “0” appears on the scale. Accurate weighing will occur when pressure is maintained.

Measuring specific gravity with heavy liquid bottles

Three properties are required to measure specific gravity using heavy fluids:

1) A stone with higher specific gravity than the liquid will sink when immersed in water. Example: Colorless sapphire (SG=4.00). It will sink in methylene iodide (SG=3.32).
2) A stone with a specific gravity lower than water will float when submerged in water. Example: Diamond (SG=3.52). It floats in its Clerici melt (SG= 4.65).
3) A stone with the same specific gravity as the water stays suspended when submerged in water. Example: Quartz (SG= 2.65). diluted with toluene suspended in bromoform brought to quartz density.

By observing how quickly a stone rises or sinks in a given liquid, an approximate estimate of its specific gravity can be made. Here is a table showing the specific gravity of different liquids:

Benzyl benzoate 1.12
Saturated salt solution 1.15
Monobromonapthalene 1.49
Carbon tetrachloride 1.59
Ethylene dibromide 2.19
Bromoform 2.89
Tetrabromethane 2.95
Klein solution 3.28
3.32 in methylene iodide
Rohrbach solution 3.58
Clerici solution 4.15
Retger’s salt 4.60
Thallium formate and malonate 4.65
Thallium silver nitrate 5.00

Heavy water should be kept in the dark when not in use. The last four liquids are dangerous and should be handled with extreme care (highly toxic and corrosive). These four liquids are not recommended for general use.

More to Read: The Optical Properties of Diamond

Cases, where a rough diamond is truly beautiful, are rare. The potential beauty of a diamond is only revealed when it is cut to reflect the extraordinary mobility and beauty of light. One cannot accurately compare the quality of different stones without knowing very well their brilliance, luminosity, color, surface gloss, and light scattering properties.

Luster, color, surface brilliance, and scattering are the inherent optical properties of diamonds. As a result of these natural features, the light movements on the diamond add beauty to it. However, these natural properties of diamonds are only revealed by human labor.

The function of light on diamonds

The light we can see is a form of radiant energy. The human eye can only see a very small part of the average electromagnetic spectrum. The electromagnetic spectrum includes infrared light, visible light, ultraviolet light, radio and television waves, X-rays, Gamma rays, cosmic rays, and all other forms of radiating energy. All these different rays have two common features:

Their speed in vacuum is equal (299,776.4 km/sec.)
They propagate in the wave motion

These electromagnetic rays differ in their frequency (vibration or cycle per second) and wavelength (the distance between two similar points on a wave. In gemology, the electromagnetic spectrum is as much a part of the electromagnetic spectrum as the light we see, X-rays, purple Other parts are also important, such as ultraviolet rays and gamma rays. The light we see shows a spectrum ranging from red (which is the longest wavelength) through orange, yellow, green, and blue to violet (the shortest wavelength). When these rays are mixed together, we are white. Wavelengths in the visible spectrum are usually measured in nanometers (abbreviated nm.) The speed of visible light is given between 380 nm and 780 nm, although there are other measurements.

Different light sources

Incandescence and radiance are considered two different sources of light. A metal glows when heated enough to absorb a ray of light that we can see, and glows when a substance absorbs light released by invisible energy (such as ultraviolet light or x-rays, electric discharge, heat, friction). Fluorescent is a type of luminescence. Fluorescence has the ability to convert short, invisible wavelengths to the long, visible wavelengths, and reflects them as ultraviolet rays like those in sunlight. If a fluorescent reaction continues even though the rays that activate it have disappeared, the resulting light is called phosphorescent.

Movement of light

When a beam of light falls on the surface of a well-polished diamond, some of it penetrates the diamond while some are reflected. The angle of incidence, in other words, the angle made by the light beam at the point of impact, and the angle of reflection are equal. These two light beams are in the same plane. The angle of incidence is measured relative to the normal angle. When the term “normal” is used, it is meant to describe an imaginary line drawn perpendicular to the surface of an object such as a stone table.

Breaking

When a light beam propagating in the air enters a material of different optical densities, it deviates from its original direction. This is called breaking. Fracture is a common occurrence in daily life, for example, if you put a straight stick in water, it will appear broken on the surface of the water. The speed of light varies according to the material it passes through. The speed of light in air is approximately 299,776 km/s. It is known that the velocity is very low when passing through denser material. Variation of the speed of light in materials with different densities causes a phenomenon called refraction.

Refractive index

The refractive index (RF) of a gemstone is called the refractive index of a ray of light that enters or reflects on it. However, the index of refraction (RF) is not expressed in terms of velocity, but rather as the ratio of the speed of light in air to the speed of light in the material it passes through.

The way light penetrates the diamond

We mentioned earlier that when light hits a denser medium, some of it is reflected from the surface and some of it is refracted inside the stone. The amount of reflected light versus the amount of refracted light is determined by three factors.

The refractive index of a stone. The higher the refractive index, the greater the surface reflection.
The flatness of the surface of a stone. If light hits a poorly polished stone, the reflected light is diffused and scattered.
The angle that light makes when falling on a stone. If the light beam falls more or less vertically on the surface, it will be refracted more than it is reflected. Thus, the more horizontally the light beam hits the surface (the greater the angle of incidence), the greater the amount of light that will be reflected.

Glare

When the upper surface of a stone is examined, the internal and external reflection intensity of white light is called glow. There are four factors that make a well-proportioned and well-polished diamond the brightest of all clear stones. These are polishing, refractive index, transparency, and dimensions. All these factors play a big role in determining the movement of light inside and outside the stone. Maximum brightness is achieved when these four factors are at their best.

Scattering of light

White light consists of many wavelengths, including all colors of the spectrum. When these various wavelengths are dispersed, they appear as different colors: red, orange, yellow, green, blue, and violet. Basically, all wavelengths of light propagate at the same speed in a vacuum, but their speeds differ in a dense material like a diamond. Each color of light has its own index of refraction, and each color propagates in different directions. When white light is scattered, the colors that make it up can appear separately.

The shimmer of many spectral colors seen in gemstones is a result of dispersion. This effect is called glow. If a stone is cut and polished in the most beautiful way, the light will be refracted and reflected perfectly to give shine to the diamond and therefore to the life that has made it precious for centuries. On a large table and a thin crown the light will not be diffused much, but on a thicker crown and a smaller table more diffuse light can be seen.

Sparkle

When a gemstone or a light source moves, flashes of light can be seen from various polished surfaces, this is called sparkle. There are four factors that determine the degree of sparkle:

The number of surfaces (facets): When a diamond is moved, the reflected light reaches the eye through the surfaces made by the person cutting the diamond.
Polishing quality: The better the surfaces are polished, the less scatter there will be, and therefore the more they will shine.
Cut quality: Correct face angles and dimensions will provide maximum visible reflections.
There is one more factor to consider. Too much surface on very small diamonds (for example, cutting .01 and .02 carat diamonds completely) will create a completely blurred image. This is not the desired effect. In large diamonds, on the other hand, the cutter can add more surface to the diamond to increase its sparkle. Some of the very well-known large diamonds have more surfaces, for example, the “Cullinan 1” diamond has 74 surfaces, the “Florentina” diamond has 127 surfaces.

Transparency

Transparency is a diamond’s ability to transmit light. Diamonds differ from each other in terms of transparency. A diamond of the best quality is the most transparent.

Brightness

Brightness can be defined as the image of the surface that reflects the light. Two factors determine the amount of reflected light; the flatness of the surface (degree of hardness) and the refractive index of the stone. These two elements affect the appearance of a gemstone’s surface. The appearance of the reflected surface is split into two categories:

Flat reflection (reflection from a flat, very well-polished surface)
Diffused reflection (reflection from a dull, matte surface) If the surface (facet) of a diamond is not polished very well, the light will be scattered, causing the stone to be less shiny. A very high-quality surface shine on a diamond is called an “adamantine shine”.

Color

There are three main factors that determine the color of an object: the light it emits, the object itself, and the eyes. Color is how the eye is affected by light. Colors fade in the dark. White light consists of all the colors of the spectrum. Different wavelengths give the material we see its dominant color. All objects absorb some colors of white light, acting as filters for wavelengths. Unlike others, absorbing only certain wavelengths makes the color perceived by the eye appear. Absorption of only a portion of the visible spectrum is called “selective absorption”. Colors differ from each other in terms of color, tone, and intensity.

The human eye is capable of distinguishing 150 pure colors in the spectrum. First, consider the colors related to the pure spectrum, red, orange, yellow, green, blue, and violet. If we start from yellow and move towards green, the middle color between these two colors is yellow-green. It is a yellowish-green color between yellow-green and green.

Hue is the degree of lightness or darkness of the color in question. Thus, white and light gray are light tones while dark gray is a dark shade of the same color. Pink is a light shade of red, chestnut is a dark shade. A light tone is generally known as a light color while a dark tone is known as a shadow. Intensity is related to the opacity or vividness of a color. The classification of intensity is as follows: LOW, MEDIUM, HIGH, EXTREMELY HIGH. E.g; The color of a blue diamond can be described as medium-dark, low-intensity greenish-blue.

It is their color, surface brilliance, sparkle, brightness, and other optical qualities that determine the extraordinary beauty of diamonds. Each of these qualities is a property of light. The different objects mentioned in this chapter are very important. You can easily imagine the movements of light hitting and reflecting off the surface of a precious stone.