Like all natural gemstones, diamonds are crystalline structures formed by geological processes and belong to the category of minerals. Among thousands of minerals, only a few dozen can be "promoted" to gemstones, with only a dozen or so common ones, and the most valuable ones include diamonds, emeralds, rubies, and sapphires. It's conceivable that minerals that can be called gemstones must have a very beautiful appearance and unique properties. Bright luster and vibrant colors are the most important factors contributing to their beauty. Gemstones undergo cutting and polishing by craftsmen. Luster reflects the reflective ability of a mineral's surface to visible light. Its intensity mainly depends on the mineral's refractive index and surface smoothness. The higher the refractive index and the smoother the surface, the stronger the luster will be. The mineral name of diamonds is diamond, with a refractive index of 2.42, the highest among gemstones, which produces a very dazzling luster, known as the "diamond luster". Gemstones are typically cut and polished. That is, the surface of a freshly processed gemstone is usually very smooth and glossy, forming a perfect reflecting mirror, making the gemstone shine brightly. With the passage of time and daily wear and tear, the original mirror surface may gradually be damaged and even become frosted, losing its original reflective ability. Therefore, the key to maintaining the bright surface of gemstones is ensuring its durability. To achieve this, the hardness of the gemstone must be sufficient, the higher the hardness, the more resistant to wear and tear. Diamonds are the hardest of all minerals in nature, making them the most resistant to wear and tear, with nothing else able to scratch their surface. With its leading refractive index and hardness, diamonds not only have the most dazzling luster but also can maintain this brilliant luster forever.
The value of diamonds can be determined by four factors: carat weight, color, clarity, and cut. All four terms begin with the letter "C", so the American Gemological Institute pioneered the so-called "4C" standard. Diamonds are composed solely of carbon and do not contain color-producing ions from the transition metals group, so diamond crystals are generally colorless and transparent. Colorless gemstones may appear monotonous, but well-cut diamonds can exhibit a variety of colors. So how do diamonds transform from being colorless to displaying colors? As we all know, sunlight is a composite light composed of seven colors. When the seven colors are mixed in equal proportions, they cannot be seen as having any color, and this is called white light. The phenomenon of splitting white light into monochromatic light and forming a spectrum is called dispersion. In physics experiments, a prism is often used to observe dispersion. Theoretically, every mineral has the ability to split white light into seven colors, but this ability varies in strength, which is measured by the dispersion value. The higher the dispersion value of a gemstone, the wider the spectral band formed by the seven colors, and the more vivid the colors will be. Among all colorless gemstones, diamonds have the highest dispersion value, reaching 0.044. The surface of a finished diamond is composed of numerous small facets, which function similarly to the prism in physics experiments. Therefore, a well-cut diamond can emit a variety of colorful and eye-catching lights. The position of the seven colors on the surface of the diamond is related to the angle of incidence of white light. Therefore, when the diamond rotates, it is equivalent to changing the angle of incidence of white light, and the colorful lights will correspondingly change rapidly and flicker unpredictably, which is extremely fascinating.
Now, we should understand that the noble status of diamonds is entirely due to their high refractive index, hardness, and dispersion value, rather than being just a gimmick. In addition, diamonds grow in the high-temperature and high-pressure upper mantle of the Earth and are extremely rare in nature, adding to their mystery and preciousness.