Diamond
Hardness 10 specific gravity 3.52
Refractive index 2.42 birefringence no diamond luster
Wear: avoid grease and impact
Diamond is a kind of "element mineral". Pure diamond is completely composed of carbon element (c). It is the only single element mineral that can be used as gem.
"Diamond" is formed in the mantle layer 130-200km deep inside the earth. Only when the temperature reaches 900 ° C to 1300 ° C and the pressure reaches 45000-60000 atmospheric pressure, can black carbon change into transparent crystal state, i.e. "diamond".
During the crustal activities such as volcanic eruption, the rocks containing diamonds in the mantle layer may be crushed due to the crustal movement. The rocks are ejected from the surface by the erupting magma and cooled instantly, so they are completely preserved on the surface layer.
Therefore, diamonds are often mined from volcanic rocks such as kimberlite and LAMPROITE.
Human understanding of diamonds
The earliest people to know about the existence of diamonds are Indians. According to Indian legend, Indian slaves found over 100 carats of diamonds by the sea 3000 years ago. Ancient Indian gem makers believed that wearing flawed diamonds would bring bad luck, while flawless diamonds would bring happiness, luck and wealth to people with pure bodies for life.
Although people now associate diamonds with love, this symbol is only popular in modern times. The main reason is that diamonds were too rare in the past. Until the discovery of African diamond mines in the 19th century, there were enough diamonds in commercial circulation.
Mining history
From ancient times to the 18th century, alluvial deposits in India and Borneo were the only known sources of diamonds, and important Brazilian mines were discovered in 1725. In the second half of the 19th century, deposits in South Africa were discovered; in the 1950s, deposits in Siberia were discovered; in the 1980s, Australia briefly became the most important diamond producing country; in the late 1990s, Canada also began to carry out commercial diamond mining.
At present, the important gem diamond producing countries include Angola, Australia, Botswana, Brazil, Canada, China, Congo, Namibia, Russia, Serra, Leon, South Africa and Tanzania.
The color of the diamond
Pure white diamond only contains C element; yellow diamond contains N element; powder diamond is caused by carbon atom dislocation; green diamond is caused by radiation; blue diamond contains B element.
Diamond maintenance
Diamonds are lipophilic, so avoid using hand cream or soap when wearing them.
Although the diamond is hard, its crystal characteristics are completely cleavage, and it may break when it is hit at a certain angle, so avoid violent impact.
The firearm of jewelry processing may oxidize the diamond surface or cause damage to the filler of optimized diamond processing. For the diamond with lead glass optimization, the ultrasonic cleaner should be avoided.
Diamond rating factors
Diamonds are rated on the basis of four main factors, known as 4C.
Carat: the weight of a gem.
Color: grade of color, relative whiteness, or rarity and beauty of color.
Clarity: the degree of inclusions and fractures.
Cut: the pecking type and quality of a cutting mill.
Diamond crystal
Diamond is a cubic crystal system, the common crystal habit is octahedron, but also some more complex crystal forms such as dodecahedron, as well as the triangular sheet twin known as macle. Triangular pits, also known as trigons, are sometimes observed on the octahedral surface.
Composition and type of diamond
The main component of diamond is C, up to 99.95%. The minor components are n (n), B (b), H (H). The trace elements are Si, CA, Mg, Mn, Ti, Cr, s, inert gas and rare elements, up to more than 50 kinds. These minor components determine the type, color and physical properties of diamond.
Type Ia: carbon (c) atom is replaced by nitrogen (n) atom, and N is polymerized impurity in lattice; colorless to dark yellow, most diamonds belong to this type.
Type Ib: C atom is replaced by N atom, and N appears as a single atom in the lattice; colorless to yellow, brown, Canary, rare.
Type IIA: free of N and C atoms, with high thermal conductivity due to dislocation; colorless to brown pink, few.
Type IIB: containing a small amount of boron (b) element; the color is blue, extremely rare.
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