Generally, the term precious stones or precious stones refers to specific minerals or rocks or various substances used in jewelry.
Specifically, some minerals or rocks that have a hard texture and beautiful colors are especially used as precious stones, e.g. the quartz with its numerous varieties.
The value of these stones is relatively high, hence their characterization as precious, which is determined mainly by the processing, the colors they present, their luster, their hardness and, of course, by their rarity in nature.
The brilliance of precious stones, created by the reflected rays of light, depends more on the treatment they have undergone, that is, the number of their flat smooth surfaces.
Their toughness also ensures their longevity over time.
Diamond
The name diamond comes from the Greek word "adamas" meaning indomitable, because due to its hardness it could not undergo any processing. It is the hardest material that exists in nature, but also the most expensive and famous! The diamond is translucent, transparent or even opaque while its colors vary. Its weight is measured in carats and its price is set accordingly.
Sapphire
Sapphire comes as a primary component of igneous rocks and is a hard mineral, while its color varies depending on the angle at which it is viewed. Despite its hardness, it carves satisfactorily offering excellent options to a jeweler.
Ruby
Ruby is a variant of corundum with a red color, which is due to the presence of chromium. Its name comes from the Latin word "ruber" which means red. In ancient times it was better known as "sapphire porphyrite" or "sapphire porphyrizon". The best color and most expensive is considered the so-called "pigeon blood".
Emerald
Emerald is a transparent, deep green variant of beryl, whose color is attributed to impurities of chromium and sometimes vanadium. The green color is a result of the presence of blue and yellow color, while the presence of Cr2O3 reduces the cohesion of the atoms making it brittle. It is one of the most expensive precious stones with an important position in the field of jewelry. The name emerald appears in the ancient Greeks as a reference to all precious green stones. From the Greek word smaragdos came the Latin "Smaragdus", which later became Esmaralda/Esmaraldus, to arrive at the English word for emerald "Emerald". The most important emerald mines are in Colombia, where every year more than half of the world's emeralds are mined!
A few words about the history of gold...
The gold in the universe is traditionally thought to have originated from nuclear fusion in < a href="https://en.wikipedia.org/wiki/%CE%A5%CF%80%CE%B5%CF%81%CE%BA%CE%B1%CE%B9%CE%BD%CE %BF%CF%86%CE%B1%CE%BD%CE%B5%CE%AF%CF%82_%CE%B1%CF%83%CF%84%CE%AD%CF%81%CE%B5 %CF%82">supernova stars.
Because the Earth was molten during its formation, it is assumed that almost all of the original gold it contained sank into its core. And the gold found today in its crust and mantle is thought to have fallen later than the initial formation of our planet, during its gradual subsequent heavy bombardment by asteroids and comets, some 4 billion years ago.
Gold has been of great economic value, as a precious metal for coins, jewelry, and other artifacts, at least since the beginning of known history. Gold reserves had become the most common basis of monetary policy.
It is estimated that, from the beginning of known human history until 2010, they were mined in total 168,300 tons or thereabouts < strong>8,740 m³ gold. Global consumption of mined gold is approximately 50% in jewelry, 40% in investment stocks, and 10% in industrial applications.
In eastern Halkidiki, specifically in the Olympiada area, there is one of the most important polymetallic gold ores in the world.
Great is the value of gold in jewelry making. Its purity is measured either in karats (24 karat is pure gold) or in millimeters (1000 millimeters is pure gold). The 14 carat (585mm) quality and the 18 carat (750mm) quality are used in the jewelry.
The value of a piece of jewelry is usually determined by the weight of the pure gold, its workmanship, and the value of the gemstones it contains. Many times the value of these stones is many times that of gold.
What do we know about silver?
The silver is one of the first metals used by man.
It was already known from prehistoric era to the peoples who inhabited the Mesopotamia, in Greece, in Middle East and in < span style="background-color: #ffffff;">Egypt.
Its current name is derived from the Latin word argentum < /strong>or the Greek argyros .
The chemical element silver is a heavy, rare, soft metal with a strong metallic luster. The content of solid crust of Earth in silver is between 0.07 and 0 ,08 grams per ton .
Silver is used to make jewelry, coins, tableware, mainly cutlery.
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