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Minerals, rocks, and biological materials that have been chosen for their beauty, durability, and rarity and then cut, faceted, and polished to create jewelry or other human adornments are known as gemstones. Although the majority of gemstones are hard, some are too soft or fragile to be used in jewelry, thus they are frequently shown in museums and sought after by collectors.
Most gemstones are unattractive in their natural condition, like ordinary rocks or pebbles, but with expert cutting and polishing, the entire color and shine are revealed. The most desired gemstones are those with clear, medium-tone, vivid, and saturated primary hues.
Formation:Â
In general, gemstones can form in one of four ways which are as below:
Igneous rare minerals or gemstones are formed deep within the earth such as Diamonds, Ruby, Sapphire, and Peridot.
Hydrothermal refers to the formation of gemstones when bodies of mineral-rich water cool, similar to how rock candy is formed.
Metamorphic, as the name implies, these are gems that have morphed as a result of intense heat and pressure such as Sapphire, Ruby, Spinel, and Garnet.
Sedimentary formation refers to when gems are formed by water depositing sediments such as Malachite, Azurite, and Opal.
Characteristics of Gemstones:Â
Optical features such as luster, luminescence or low-temperature light emission, dispersion of light which is the separation of distinct wavelengths of light, refractive index and absorption spectrum are all characteristics of gems. Physical qualities such as specific gravity, hardness, cleavage type, and breakage of the material without separation of the parts are also used to classify gemstones.
Mineral vs Non-Mineral Gemstones:Â
Although most gemstones are minerals, there are a few that aren’t. Minerals are inorganic substances with specific chemical compositions and crystalline structures that occur naturally in the Earth’s crust. Color, hardness, crystal shape, specific gravity, luster, fracture, and tenacity are among the characteristics that distinguish minerals. We call a mineral a gemstone when it is considered rare and extraordinarily beautiful (for instance diamond, emerald, ruby, and sapphire). Minerals can be gemstones, but gemstones can’t always be minerals.
Non-mineral or organic gemstones, such as pearl, coral, amber, ivory, and jet, are made from living organisms such as animals and plants that have evolved into magnificent gemstones through natural processes.
Determining the value:Â
The “4 C’s” (carat, color, clarity, and cut) are used to determine the value of a gemstone. The Mohs’ scale, on which 10 is the hardest, is used to assess hardness. (The hardness of a diamond is ten.) The Mohs hardness of gemstones should be at least 6. A stone with a hardness of at least 7, which is the hardness of quartz, should be considered extremely durable.
The beauty and rarity of a gemstone, as well as the size of the stone, determine its worth. The carat, as a unit of measurement, is used to determine size. 0.2 grams equals a carat (0.007 ounces). (A 10-carat diamond is 2 grams, or 0.07 ounces, in weight).
Precious and semi-precious stones:Â
Precious stones are defined by their high quality, scarcity, and color attractiveness. Diamond, sapphires, ruby, and emerald are the only four precious stones thus, every other gemstone is classified as a semi-precious stone. Their hardness, which translates to scratch resistance, also contributes to this differentiation. If one stone can scratch the other, it is harder than the other.
The phrase “semi-precious stones” does not imply that they are inferior to precious stones in terms of beauty. Amethyst, topaz, peridot, citrine, aquamarine, and green tourmaline are the most well-known of these. Semi-precious stones have a limitless palette of colors and hues, far greater than the total number of colors found in precious stones. It is always preferable to use a lovely aquamarine over a poor-quality sapphire.
Some Important Gemstones:Â
Diamond is the hardest substance known to exist in nature, with a Mohs hardness of 10. It’s made up entirely of carbon that’s firmly packed into a cubic structure. Carat, cut, clarity, and color are the four Cs that are used to grade diamonds.
- Ruby is a corundum variation with a Mohs hardness of nine. When chromic ions replace some of the aluminum ions in the crystal, it turns red.
- Sapphire is made of corundum and has a hardness of 9. It is similar to ruby in that it is made of corundum and has a hardness of 9.
- Emerald is a variant of beryl, a beryllium silicate with a hardness of 7.5 to 8. Emerald is a variety of beryl, a beryllium silicate, with a hardness of 7.5 to 8. Small levels of chromic oxide are responsible for the green hue.
Conclusion:
So, we can conclude by stating that any of a variety of minerals that are prized for their beauty, longevity, and rarity are called gemstones. A few non-crystalline organic materials (e.g., pearl, red coral, and amber) are also classified as gemstones. Fewer than 100 of the over 3,500 identified natural minerals are used as gemstones, and only 16 have achieved significance. Some of these (for example, beryl and corundum) provide more than one type of gem. In almost every case, the minerals must be cut and polished before they can be used in jewellery.
