There is something called the diamond miner’s dilemma.

Diamonds are extracted from the ground. If they are in the igneous rock known as kimberlite they are usually sorted with automated equipment.  Previously this automatic equipment would reduce the kimberlite to pieces of ore 30mm or less in size. Unfortunately there may be diamonds much larger than this 30 mm size. The dilemma miners face is that the sorting machine that looks for the diamonds may actually be breaking the largest diamonds as they work. Though diamonds are extremely hard they will break if hit along certain points. Recent changes to equipment have been aimed at rectifying the situation.

For the last two years X-ray machines have been used at mines like South Africa’s Karowe mine. The X-rays look for diamonds before the ore is sent to be crushed. In November 2015 the second largest white diamond was discovered at this very mine, followed by two other diamonds in the following days.

The largest diamond every discovered was the Cullinan, extracted by hand over 100 years age. The fact that no other comparable diamonds have been discovered in the intervening years suggests the mining process, using explosives and ore crushing machines, may have been inadvertently destroying some sizable gems.  Needless to say the present extraction methods are rapidly undergoing change.