Diamonds

The name diamond is derived from the Greek word adamas which means invincible. It was given in reference to diamond’s great hardness. Diamonds are the hardest mineral on Earth, and this combined with its exceptional luster and brilliant fire has made it the most highly prized of all gems. Pure colorless diamonds are the most popular but other varieties from yellow, brown, pink, red grey and black are also found depending on the impurities present. Large diamonds are rare and are though prised very highly. They have a hardness of 10 on Moh's scale and therefore can be polished only by other diamonds. even as hard as it is, it is not impervious. Diamonds have four directions of cleavage, meaning that if it receives a sharp blow in one of these directions it will cleave, or split. A skilled diamond setter and/or jeweler will prevent any of these directions from being in a position to be struck while mounted in a jewelry piece. As a gemstone,

Diamond's single flaw (perfect cleavage) is far outdistanced by the sum of its positive qualities. It has a broad color range, high refraction, high dispersion or fire, very low reactivity to chemicals, rarity, and of course, extreme hardness and durability. Diamond forms at extremely high temperatures and pressures, conditions that are only possible very deep in the Earth’s crust or even the upper mantle, 80kms (50miles) or more underground. The discovery of diamond was done in 1879 in kimberlite rock in South Africa. Today, Australia is the main producer of diamond. Large diamonds, particularly large diamonds without flaws, are extremely rare. . Diamonds are transparent over a larger range of wavelengths (from the ultraviolet into the far infrared) Diamond conducts heat better than anything i.e. five times better than the second best element, Silver. Diamond has the highest melting point (3820 degrees Celsius and its Specific Gravity is 3.5 (above average). Its refractive index is 2.4 ( very high) and dispersion is 0.044, fluorescent. 

Gemstones

Largest Diamonds in the world

KOH-I-NOOR

("Mountain of Light") is one of the worlds largest diamonds, it weighed in at 186 carats when it was first discovered in 1304. This oval shaped cut stone is believed to have been set in the famous peacock throne of Shah Jehan. Re-cut during the reign of Queen Victoria it now weighs 108 carats and forms part of the British Crown Jewels.

The Cullinan II is a cushion shaped diamond weighing 317,4 carats. It is the second largest diamond in the world and was cut from the same rough diamond as the Cullinan I. The diamond is in the center-front of the British Imperial State Crown.. It is also known as The second Star of Africa.

The Cullinan I is a pear shaped diamond weighing 530.20 carats. It measures 53mm x 44mm x 29mm, and has 76 facets (counting the culet and the table). Cullinan I was cut from the largest diamond ever found, the Cullinan and adorns the sceptre of King Edward VII and is on permanent display in the Tower of London. It is possible to remove the diamond from the Royal Scepter to wear it as a pin or pendant. This diamond is also known as “The Great Star of Africa”.

The Millennium Star is a pear-shaped diamond weighing 204,04 carats. It is the world’s second largest diamond in the top colour-grade D, internally and externally flawless, cut to perfect proportions. The rough diamond was weighing the magic number of 777 carats. The first is the 273.15 carat Centenary Diamond.
 

The Centenary, was discovered at the Premier Mine of South Africa on the 17th of July 1986 and joined the ranks of the worlds largest diamonds, it weighed in at 599.10 carats in rough form. Master-cutter Gabi Tolkowsky took almost three years to complete its transformation into the world's largest, modern-cut flawless diamond. The Centenary has 75 facets on top, 89 on the bottom and 83 on the girdle, for a total of 247 facets. It weighs 273.85 carats and now forms part of the British Crown Jewels.
 

The Blue Hope another of the worlds largest diamonds was once owned by Louis XIV and officially designated the *blue diamond of the crown*. It was stolen during the French Revolution but showed up again in 1830 and was bought by Henry Philip Hope of London, the diamond was named after the new owner. The Blue Hope Diamond is believed to carry a curse, two of the owners had their entire family die just one year apart. It now resides in the Smithsonian in Washington where it is recognized as one of the worlds largest diamonds.
 

THE EXCELSIOR

The Excelsior which means "higher" is not only one of the worlds largest diamonds it is the second largest diamond ever found. It originally weighed 995.2 carats. The diamond was cut into ten pieces, the three largest weighing 158, 147 and 130 carats. These pieces were then cut into 21 gems ranging from 70 carats to less than 1 carat. An African mine worker found the diamond as he was loading his truck, he kept the find secret until he could safely turn it over to the mine manager who rewarded him with some money, a horse and a saddle.