I have been in the jewelry business for over 52 years. As a gemologist I am intrigued by the characteristics of the diamond. The diamond tops Mohs hardness scale coming in 140 times harder than its closest competitor, the ruby and sapphire!
That is one of the reasons it has been chosen as the stone for marriage. Many years ago the Diamond Trading Co., also known as De Beers, established the moniker: "A Diamond is Forever!" You might compare that to the Biblical statement about marriage: "What God has joined together, let no man separate!"
For the majority of my career diamonds came from one source, the earth's crust. This process requires moving massive tons of earth using heavy equipment and many man hours of labor, often causing detriment to lives and the environment! With this understanding, it is easy to see why the earth mined diamond would cost as much as it does. Also, you might want to explore how De Beers controls the supply to be equal with demand.
In July 2018, the Federal Trade Commission released a statement claiming that a diamond is a diamond regardless of origin, the earth or a laboratory. With that ruling, I began selling laboratory created diamonds as well as earth mined. A point of information, the earth mined diamond will sell for as much as twenty times the price of the laboratory diamond.
This picture shows an F/color VS2/clarity 3.10 carat Emerald cut laboratory grown diamond in a 14K white gold halo style mounting. The price is $5,000. If we set this ring with an earth mined diamond with the same color and clarity, the price would be $50,000! The beauty is the same, but the choice is yours!