Since about 75% of all diamonds mined are used by industry -- not gemstone quality, most are sold nearer the excavation locations, as a matter of economics than those which are transported to diamond processing locations, such as Antwerp, London or New York City.
Diamond mining takes place in many African countries, Canada, India, Brazil, and Australia, and industrial diamonds are available for sale in these locations.
You can read more about the diamond industry, below.
With appropriate land ownership or leasing rights, you can mine diamonds on every continent except Europe and Antarctica.
You can see the Golden Jubilee diamond, now 545.67 carats, in the Royal Thai Palace as part of the crown jewels when they are in view.
Since diamonds are extremely highly valued relative to their size, the repository of 'the most' diamonds is not public knowledge.
Given from your question you want a statistical assurity of 100%, your best source will be to look in a jewelery story that sells diamonds.
Probably a jewelry store.
Diamonds diamonds and more diamonds
You can pick up diamonds from the earth at the Crater of Diamonds State Park in Arkansas.
Debeers diamonds are the standard by which most diamonds are measured.
The most common use of diamonds is for industrial tools, because industrial diamonds are the most common diamonds.
Oregon is not known for its raw diamonds.
Yes, diamonds can be naturally red. In fact, these are the most rare of natural diamonds.
Outer space. No planet, no rocks. No rocks, no diamonds :(
Most jewelery stores in most cities in Europe sell diamonds.
Diamonds are cut in the Netherlands, in India, in Canada and Australia. India may cut the most diamonds, since most small stones are cut there.
Yes, diamonds can be found underground. In fact, most diamonds are mined from the earth.
Diamonds come in all sizes: 20% of which are gem-stone quality, the remainder are industrial diamonds. Most diamonds are tiny: gem-stone quality diamonds must be larger than most diamonds found, because of their use. Gem-quality diamonds must be visible, which is not true for industrial diamonds. Your answer, then, by logic, dictates that most diamonds an average diamond is much smaller than a pea.