The white tones have been done alloying nickel, zinc and copper with gold traditionally, but more recently the silver and the palladium have replaced zinc. stos treatments of variations of color of gold are used mainly in jewelry shop. The gold is a remarkable, rare metal, with a combination without pair of chemical and physical characteristics. It is the unique yellow metal and it takes his name of the old English word for the yellow, ' geolu '. It is also the unique metal that does not form any film of oxide in him is superficial in air in the normal temperatures, meaning that never it will turn rusty or tarnish. The fineness is a metallurgical term that indicates the purity of gold and it are expressed in parts by 1.000. The gold currencies and bars have a fineness of 999.9 portions by 1.000.
The purity of gold in an article or the amount of gold in an alloy is moderate with a called unit a carat. An article of fine or pure gold is of 24 carats, and in the one of few carats indicating is valued the fine gold content of the proportion like fraction of 24. For example, an article of gold of 18 carats contains 18/24 (or 3/4) fine gold and 6/24 (or 1/4) of alloy in weight. Characteristics of gold a combination without pair of characteristics physical chemicals and make inestimable gold to an ample range of daily uses. The gold is less reactive of all the metals. A metal is called " noble" (a term alchemist) because it does not oxidize under ordinary conditions, meaning that never will never turn rusty and will tarnish. The physical characteristics of gold of the electrical high conductivity and inertia of the chemical agent do an excellent and reliable conductor to him, particularly in rough atmospheres, where the temperatures can extend of -55? C to 200? C.