Gemstones are precious or semi-precious stones that are cut, polished and set to create beautiful pieces of jewelry. Most are made from minerals and rock and are mined from the Earth. However pearl and coral are often classed as gemstone as well. Gemstones are highly prized for their amazing colors and surface textures. Some of the most well known gemstones are sapphire, diamond, rubies, emerald and amethyst.
How do gemstones form?
Most gemstones form in the Earth crust which is the top layer of the Earth, which means that they are found approximately 3 to 25 miles beneath the Earth. Some gemstones, such as diamonds are found much deeper than this and form in the Earth’s mantle. The Earth’s crust has many different sized volcanic pipes running through it. Magma, or hot molten lava, runs through these pipes from the Earth’s mantle (central layer). Magma that reaches the Earth’s surface cools and is called lava, which often solidifies. If the magma does not reach the surface it cools slowly within the crust and crystallizes and forms minerals. The crystallization and pressure of the surrounding rock and Earth forms gemstones. Different gemstones form in different types of rock. The quartzes (including amethyst, citrine and ametrine) , the garnets, moonstone, apatite, diamond, spinel, tanzanite, tourmaline, topaz and zircon are all formed in igneous rock. Jasper, malachite, opal and zircon are formed in sedimentary rock and the beryls (emerald, morganite and aquamarine), jade, lapis lazuli, turquoise, spinel, ruby, sapphire and zircon are formed in metamorphic rock.
How are gemstones mined?
Although the mining of each gemstone is different there are also some similarities. If gemstones are relatively close to the Earth’s surface they can be mined using an open pit mine. The top surface of the Earth is excavated to reveal the mineral vein (the volcanic pipe where the magma cooled). The rock is then mined and taken to a processing facility where the gemstones are separated from the rock or ore. If the gemstone is found in one of the Earth’s deeper layers then an underground mine is constructed and the rock containing the gemstone is mined from under the ground. Once a gemstone is separated from the surrounding rock and is in its raw, uncut stage it is taken to professional cutters and polishers who turn the gemstone into usable stones for jewelry. Some jewelers prefer to buy it in raw form and cut and polish it personally. Some gemstones, such as pearls, are mined in a unique different way due to where they are found.