More than 5 million diamonds need to be mined in order to get 2 carats gem quality diamond. For this reason prices of diamonds go up according to their weight, two diamonds of one carat will be cheaper than one, 2 carat diamond
Over 80% diamonds that are mined fit only for industrial needs. And even between those “Gem” quality diamonds, most are not clean or have less valuable colors .
One more reason for diamonds being expensive, out of the fact that diamonds are rare. The mining is extremely expensive. more than 40 tons of gravel and sand needed to be processed in order to recover one carat diamond from the world’s diamond deposits