What are Gemstones?

1. What are Gemstones? A gemstone is the name given to a piece of mineral (or other rock or organic material) that after it has been cut and polished has been made into a piece of jewellery or another accessory. Gemstones are minerals, rocks, or organic matters that have been chosen for their beauty, durability, and rarity and then cut or faceted and polished to make jewellery or other human adornments. Even though most gemstones are hard, some are too soft or fragile to be used in jewelry, so they are often exhibited in museums and sought by collectors. Gemstones Formation Our planet, which was created about 4.5 billion years ago, is comprised of several layers: the Earth’s crust, ranging from 3 to 25 miles deep, the mantle and the inner part of Earth known as the core. Most of the gemstones form as minerals under various conditions in the rocks of the Earth’s crust, while just a few of them form in the mantle. The crust is made up of three kinds of rock, known in geology as igneous, metamorphic and sedimentary rock. All gemstones are mined in the crust. After they are mined, they usually go to a lapidary, which does the final cleaning. This may involve grinding off the matrix or rock, in which the gemstone was buried, and then cutting or faceting and polishing the gemstones. A gemstone that has been cut and polished is called a gem, or jewel.

2. Gemstones Colour Gemstones are diverse in their beauty, and many are available in a stunning variety of shades and colours. Most gemstones have little beauty in the rough state, they may look like ordinary rocks or pebbles, but after a skilled cutting and polishing the full colour and lustre can be seen. Generally, gemstones with clear, medium-tone, intense, and saturated primary colours are most preferred. Gemstones Clarity Gemstones are formed below the Earth’s surface and can sometimes show traces of other minerals, called inclusions. Inclusions can look like small spots or imperfections within the stone. When viewed through a microscope or a 10x loupe, they can give information about the geological environment in which the mineral was formed and its origin. Inclusions can sometimes identify gemstones and even prove whether the stone is natural or synthetic. Some gemstones, such as emeralds, are more likely to have inclusions. Others, such as aquamarine and topaz, generally have very few inclusions or even none at all. Gemstones Carat The weight of the gemstone is measured in carats (5 carats = 1 gram). It’s important to recognize that some gems are denser than others. For example, a one-carat ruby (very dense) is going to be smaller than a one-carat emerald (less dense). Also, different types of gems that are similar in size may still differ significantly in value. Gemstones Cut The natural beauty of a gem can be enhanced by the way it is cut. There are two basic kinds of gem cuts: cabochon and faceted. The cabochon cut has a smooth rounded top, usually with a flat base, and it is mainly used for opaque or translucent softer gemstones. Cabochons were the only way in which stones were cut until about the 14th century when faceting was developed. Faceting is the process of cutting a gemstone to improve its beauty by making it reflect more light. The faceted cut has many flat cut surfaces (facets) with an overall shape that might be round, oval, square, and more. Only the harder gemstones can be successfully faceted. A gemstone that has been cut and polished is called a gem, or jewel. Gemstones Species and Varieties Many types of gemstones belong to groups or species which share a common crystal structure and chemical composition. Some of the most important gemstone species include beryl, corundum, garnet, quartz, and tourmaline. Further, each species may have one or more varieties, which have special colouring or features. For instance, the species corundum includes the varieties ruby and sapphire. However, not every gemstone variety belongs to a group, many are unique varieties that don’t share properties with any other kind of gem. For instance, peridot, zircon, topaz, and spinel.