Diamond is the hardest known mineral, forming deep under the Earth's crust for several millions of years. The youngest diamond in the world is app. 5 million years old. Why is its price so high? Diamond is not only expensive, because it is rare and has beautiful shine, but also because it forms deep underground and because to excavate it, there is so much machinery and manpower required (one point of interest, by excavating 1t of mine, we obtain approximately a diamond the size of 1ct). Among all the excavated diamonds, there is a very small percentage of such, which are suitable for further cutting and use in the goldsmith's trade. In Zlatarna Celje we issue a certificate for each piece of jewellery with an engraved stone, containing the information about the diamond and confirming its quality.