Why are diamonds expensive?

The preventive study of geologists for the geographic location of areas prone to extraction, together with the physical achievement of the necessary equipment, already involves a strong commitment in terms of investment as diamond mines are often found in inaccessible and inhospitable areas. Mining in places like Siberia and Canada make the process complex and extremely difficult due to the frozen terrain and polar temperatures, the inaccessible areas of Africa and Australia that present new challenges that are increasingly difficult generate very high costs. A factor not to be underestimated in the management of diamond mines is the volume of minerals that must be extracted to be crushed and washed trying to recover the diamonds, it must be considered that very often the workers must extract about a ton of rock to extract a diamond jewelery whose weight is around 0.25 cents of a carat which has a diameter of 4 millimeters. As with most of the products we buy, quality and rarity increase the price. Low quality "industrial" diamonds make up the vast majority of rough diamonds recovered from most mines.
Depending on the size of the mine, it may be necessary to extract and process 100,000 tons of kimberlite (the rock where the diamond is found) to produce a single piece of blank. The rarity of a high quality diamond will be reflected in its price. It is possible to get a precise idea by observing this video which briefly shows the history of the diamond https://realisadiamond.com/app/uploads/2019/10/DPA_LongVersion_Cut57_FrontTitle.mp4