A precious or semi precious mineral, rock or stone that can be cut and polished for use as a gem, these colourful objects are frequently used in jewellery but also for a wide variety of other purposes as well. Among the most highly valued are Diamonds, Emeralds, Rubies and Sapphires and those which are less precious but just as well known include Turquoise, Tigers Eye, Lapis Lazuli and Malachite to name just a few. Many of the most prized gemstones are found in museums or private collections.
The word 'gem' (an abbreviation of gemstone) is often used to describe someone who is considered to be special, highly thought of or 'treasured', for example 'you're an absolute gem'. In using this term we are subconsciously making a comparison to something of great beauty, something of immense value and something which is unique, rare and highly sought after.
Their unique quality has been valued for thousands of years all around the world by people of almost every culture, race, colour and creed and gemstones remain as popular today as they have always been. It is not entirely known why primitive man started to collect them, it may have been because of their colour, crystal like shape or simply that they were generally harder than anything else he had ever come across before. Whatever the reason, there must have been something special which attracted the attention of whoever first bent down to pick this material up and which subsequently caused them to keep it, to take ownership of it and to possibly wear it.
The purpose of wearing and/or owning gemstones and jewellery has changed throughout history, however they have always been worn as a symbol of status and wealth and hence some magnificent examples adorn the crowns of royalty. They are also a visual reminder of someone's success and achievement to both the wearer and those with whom they come into contact.
Many are attributed with having mystical powers and an energy which is unrivaled to any other tangible object, they are believed to have healing powers and have been carried as amulets and talismans for thousands of years. There are many tales about those which bring luck or those which are believed to inflict a curse or carry bad luck. They are indeed quite magical for many reasons and continue to fascinate mankind as they always have. To be considered a gemstone, there must be three attributes present, beauty, durability and rarity.
Gemstones are naturally occurring materials that form in rocks and sediments. Each mineral or mineral group has a particular chemical composition made up of the same elements or chemical ingredients. In addition to the main elements, there may be other elements that do not appear in the chemical composition and it is these which may affect certain properties such as colour. In terms of chemical composition, the largest group consists of silicates and the second largest is oxides. Emerald is a silicate of Beryllium and aluminium otherwise known as Beryl and Rubies and Sapphires are composed of aluminium oxide otherwise known as Corundum. Diamonds are a crystalline form of carbon. With regards to corundum, the family to which Rubies and Sapphires belong, pure corundum would be colourless but in nature, pure or perfect rarely exists, so corundum is usually coloured. Chromium and Vanadium are accessory elements which make a Ruby red and Iron and Titanium make a Sapphire blue. Other combinations are the cause of different colours within the corundum group such as green, yellow and pink.
Interestingly there is no geological definition for the word gemstone because it is a human creation. Minerals are formed by geologic processes in rocks in their natural environment and when we excavate precious or semi precious material and cut and polish it, only then does it become a gemstone.
Some varieties such as Lapis Lazuli are classified as rock meaning they are composed of a mixture of minerals whilst others are made of organic matter, for example Pearl is produced by Oysters, Amber is fossilized tree resin and Jet is a form of coal.
Value is usually determined according to beauty, rarity, durability, size and often shape is also taken into consideration. Other characteristics which are also important are colour and any unusual optical effects such as chatoyancy, iridescence and play of colour. Gemstones can also be cut (faceted) to enhance and/or optimize features.
Further reading:
Gemstones
| ← Gemmy | Gemstones and Jewellery → |
|---|
