Diamonds
 
 
What´s a Diamond made of ? 

A diamond consists of pure, cubic crystallized carbon and has a very high refractive index, best known from brilliants.  
Diamond is also well known to be the mineral with the highest possible grade of hardness (10 on the scale of Mohs).  
 
 
 
 
 
 
 

How is a diamond born ? 

      A Diamond is born in the interior of the earth in a depth of  80 - 120 km at temperatures of 1100-1300 °C and very high pressure. Volcanic eruptions bring Diamond to the surface of the earth. That´s why it occures in old volcanos (primary occurance). Erosion comminutes and transports the mineral and so diamond also occurs in rivers (secundary occurance) and even in the sea (tertiary occurance)
 

Occurance of diamonds 

       
The first diamonds are supposed to be discovered in India, in 1725 diamond-occurances in Brasil were disvovered and Brasil became the most important supplier of the 18th and 19th century.  
In 1867 diamond were discovered in the Oranje-river of South-Africa.  

Until 1871 diamonds were mainly discovered in secundary occurances, only lucky chance made the discovery of South-Africas primary occurances (in volcanos) possible. Volcanic pipes still make South-Africa to the largest supplier of diamonds in the world. Other occurances of diamonds were discovered in Namibia (since 1908) and GUS (since 1829).  

       
What determines the price of a diamond ? 
 
Four factors are international known to as the "four C´s":  Colour, Cut, Clarity and Carat (Weight in Carats = ct)  
The colour of diamonds is graded by using two different scales: an international and an American graduation-scale (D- Z). The colour of diamonds is mainly caused by nitrogen-atoms in the carbon-grating that colour diamonds yellow with increasing concentration.   
The following table shows the most common  colours:  
 
 
 
 
 
 
 
 
 

 
 
 
International gradation
American gradation
           River
D
E
           Top Wesselton
F
G
           Wesselton
H
           Top Crystal
I
J
           Crystal
K
L
           Top Cape
M
N
           Cape
O
           Yellowish
           Light Yellow
           Yellow
Z
 

      When grading a diamond´s cut an expert not only graduates the cut, but also the polish, the symmetry and the finish of all facettes.  
        
        

      The Clarity of a diamond is graduated with a 10 x magnifying glass. An expert also takes inclusions, fissures and cavities into account and finds a cathegory in the following table.

 
International
IF.......Inernally flawless 
VVS....Very very small inclusions 
VS......Very small inclusions 
SI.......Small inclusions 
P1......1st   Pique´ 
P2......2nd Pique´ 
P3......3rd Pique´ 
  
      The weight (Carat) of a diamond is measured in Carats. 1 Carat is 0.2 g and equal to the average weight of  one seed of the St. John´s bread. But don´t confuse the weight Carat with the standart for precious-metal alloys Carat !