The term diamond originates from two Greek words: "adamas" (indomitable) and "diaphanes" (transparent).
Already in the "Naturalis historia" by Plinio il vecchio (1st century AD) the diamond is considered the hardest stone, and immediately achieve a symbolic meaning linked to its properties.
Consists of a crystal lattice of carbon and its unit of measurement is the carat (this too is a word of Greek origin, from "kerátion", from the seed of the carob tree, which was used to measure very small amounts) same of 0.2 grams. To crystallize into diamond, however, carbon needs a very special process that can take place at a depth of 150-200 km, commonly referred to as the Earth's upper mantle Asthenosphere, with at least 50.000 times the atmospheric pressure and temperatures between 900 and 1200 degrees centigrade.
Afterwards, the diamonds were able to rise to the surface thanks to a special type of eruption, characterized by a high rate of ascent of magma and a sudden cooling which prevented the diamonds from turning into graphite.
These eruptions, however, have not been happening for at least 500 million years and today the remaining traces are a particular geological formation known as "Camino di Kimberlite" or "Diatrema", which relies on regions which have not undergone geological changes, such as southern Africa, Siberia, Australia, Canada or Brazil.
They constitute the most important deposits, since the magmatic rock of which they are made and that is called Kimberlite (named after the town of Kimberley in South Africa) conserve stuck inside the rough diamonds. In addition, as a result of erosion on Kimberlite weathering, other deposits are found in oceanic terraces or along the path that led them to the sea for flood runoff.
Peculiar properties of diamonds
hardness: it is the hardest material that exists in nature (grade 10 of Mohs scale), no material except another diamond can scratch, wear or penetrate it;
gleam or brilliance: in the classification of non-metallic gloss mineral (transparent) it occupies the highest position called "Adamantina".
Compared to the incident light, the reflection is specular, the absorption is practically null making it completely transparent and the refraction has a very high index (almost 2.5) besides with the ability to maintain speed of light equal in all directions (mono refractivity);
brightness: the combination of high quality of Diamond Cut and Shine, give to diamond the unparalleled brightness making it coveted all over the world;
resistance: it is resistant to chemicals making it "eternal";
thermal properties: it is one of the best heat conductors that exist in the face of a minimum thermal expansion;
heat resistance: it melts at 4000 degrees centigrade but in the atmosphere at 1500 degrees centigrade temperature becomes graphite, which in any event allows it him to withstand fire.