Prior to that, diamond jewelry was worn almost exclusively by royalty. The earliest example of diamonds being placed in a setting dates from the time of the Norman Invasion of England; at that time, one of the Árpád kings of Hungary, possibly Andrew I, had rough-cut diamonds set into a crown for his queen. However, cut diamonds would not be available for another half-millenium.
The mid-1500's were an energetic time; Martin Luther of Germany and Henry VIII of England had broken with the Church of Rome; Ivan IV (the Terrible) expanded Russia to its present-day borders, and Ottoman sultan Suleiman extended the Turkish empire as far west as Vienna. It was during this time of ferment that the first diamond-cutters' guild was formed in Antwerp, located in present-day Belgium. An industry soon developed for the purpose of appraising loose diamonds, giving birth to the modern diamond jewelry market. Antwerp continues to be the center of the international diamond jewelry trade.
The gems that are used in diamond jewelry is 75% science and 25% art. Together, these make up the "4 Cs" that are used to evaluate loose diamonds:
- carat
- color
- clarity
- cut
Although we generally think of clear or white diamonds, they come in a wide range of "colors" ranging from crystal-clear white to dark amber. Pink, green, blue and even purple diamonds are not unusual, and some are far more valuable than their white counterparts.
"Clarity" refers to just that - how clear the stone appears. All natural and artificial diamonds have internal flaws; the fewer or the less apparent these flaws are, the higher the appraisal is likely to be.
These three qualities are objective, and easily measured and quantified. "Cut" is a more subjective quality; selecting gems that are appropriate for use in diamond jewelry requires a good eye and aesthetic sense.
Of course, loose diamonds are not really jewelry until they are placed in a setting, such as a ring or necklace. Even the finest diamonds' value can be affected by the setting; it is a value-added aspect of diamond jewelry.