This person works as a gemologist.
A person who mines diamonds is called a miner.
Diamonds made in factories are called man-made diamonds.
A group of judges is called a panel.
a person who cuts and polishes gems is called a gemcutteror a lapidary (sometimes lapidarist).
The gemstone that is often confused with diamonds is called a cubic zirconia. A person should have their ring checked by a jeweler if they suspect it's a fake.
Loose diamonds are called loose diamonds. When set as a group, the term may describe the setting more than the stones, i.e., pave, which is a 'pavement' of diamond stones. Otherwise multiple diamonds are simply called diamonds.
a diamondologist which is a subset of gemologists (study all precious and semi-precious stones)
This person is called a gemologist. There may be a sub-definition of this job title particular to one who selects diamonds all day, but overall, this person trained and is probably certified as a gemologist.Read more, below.
Coal has been called 'black diamonds'. This is probably because coal and diamonds are both formed from carbon.
They are called blood diamonds because the money made from them is used to fund wars and terrorist activities.
Diamonds are VALUABLE
Man-made diamonds are usually called man-made diamonds.