Formation of Gemstones

Valuable gemstones are extracted from the earth’s core and include mineral rocks, diamonds and stones in a variety of colors;, for example, rubies, emeralds and sapphires. While the diamond is still the world’s most precious and well-sought after stone among all, we can see a rise in demand for various other gemstones as well. Not that they were not valued any time before, but in recent times, people have shifted their interests towards gemstones other than diamond, and in fact, most of the engagement and wedding rings now hold a semi precious gemstone in center.  However, just as their demand and value has been on the rise, so is the need to authenticate their originality.

Almost all gemstones are found in the crust of earth. However, there are two which are found deep below in earth’s mantle: Peridot and diamond. There are kimberlitic pipes below the earth which is the main passage for diamonds to surface up. Through these pipes, molten magma flows and as it reaches the surface, it collects foreign rocks known as xenoliths on its passage. Diamond is one of the rocks, which are assimilated on the way and brought up the surface through volcanic eruptions.

Igneous rocks

Igneous rocks are those that are formed when the molten magma beneath the earth cools down and starts to crystallize. Igneous rocks include two further types further: intrusive, which are formed beneath the surface when the magma cools down, and extrusive, which are formed when lava cools down above the surface of earth.

At the time of cooling, there are many minerals present which starts to combine and form a crystallized structure. This is how gemstones are formed. Environment, cooling time, pressure, temperature – all these factors play an important role in forming each of the gemstone. Larger gemstones will be formed if the cooling process is slower. Diamonds, spinel, Peridot, quartz, moonstone, topaz, tourmaline, zircon, citrine, and amethyst – these all are the most common types of igneous rocks.

Sedimentary cycle

Sedimentary cycle is the second most important process in the rock formation. Rocks formed through this cycle are not actually formed, but rather found. Due to the process of weathering over the time, many rocks are washed down with rain, wind and river and deposited into the sea or riverbanks. There, they keep accumulating along with other organic and inorganic material mixing into it, such as plants, mud, shells. As the time passes, these mixtures are compressed and compacted to form hard rocks. Most of the time, those rocks will be found in sedimentary rocks that have been originally weathered from their parent rocks, which then can be igneous or metamorphic in nature. Common rock minerals found in these sedimentary deposits include Beryl, Opal, Turquoise, Malachite, Azurite, Chrysoprase, Chrysocolla.

Third source of gemstones are the metamorphic rocks. As the name suggests, these rocks are formed when already existing rocks goes through a change process due to pressure changes or changes in temperature. The process is called recrystallization, since during this process, molecular structure of these rocks is broken down and restructured, forming a completely new rock, with same basic composition but different structure. Some of the common metamorphic rocks are garnet, tanzanite, sapphire, ruby, kyanite and emerald.

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