Cross FineJewellry

Diamonds have been sought after for centuries as the rarest and most precious of gems. Billions of years ago, below the earth’s surface, extreme forces of heat and pressure transformed carbon into diamond crystals. These diamond crystals were first discovered around 800 BC in riverbanks and it wasn’t until around 150 years ago that diamonds were discovered hidden in Kimberlite rock formations.

The forces pushing these formations to the earth’s surface were so extreme that only a few crystals surfaced, hence the rarity of the diamond. Diamonds are the birthstone for the month of April. Besides being the most popular gemstone for engagement rings, diamond is the accepted anniversary gem for the 10th and 60th years of marriage.

The name ‘diamond’ comes from the Greek word ‘adamas’ meaning unconquerable suggesting the Eternity of love. In fact, diamonds have been the traditional symbol of love since ancient Greece.

Diamonds are internationally graded under the standards of the 4C’s (cut, colour, clarity and carat weight).

The 4C’s - Cut

Cut must not be confused with shape. Cut 'Make' is assessed over 3 critical aspects. Symmetry, Proportions and Polish. When these aspects are perfect a brilliant cut diamond is considered a 'triple excellent'. A well-cut diamond fetches higher prices. A better cut stone has quite obviously more sparkle and ‘is more alive’ than a poorly cut diamond.

As you can see, when symmetry, proportions and polish are excellent the light that enters is dispersed back through the diamond’s top facets. When a stone is cut too shallow, too deep or lacks exact symmetry and is poorly polished the light that enters is allowed to escape or is diverted or dulled off and will not display maximum scintillation.

The 4 C’s – Colour

The most sought after diamonds are those that have no colour. It is this lack of colour, that makes these diamonds the most valuable. The finest colourless diamonds are known as ‘D’ colour, and as other colours taint this pure whiteness the colour grade of a diamond is decreased. The following table outlines the colour grading scales used by the Australian and New Zealand Industry. Diamond colour is determined via a visual assessment and/or with the aid of an electronic colour-grading machine.

The colour diagram above is not exact. Colour differences in diamonds are subtle.

The 4 C’s – Clarity

Clarity refers to the level of inclusions, the natural imperfections a diamond possesses. These may be internal or external to the diamond. The fewer inclusions, the rarer and more valuable the diamond.

Clarity is defined using the following scale:

The 4 C’s – Carat Weight

Diamonds are measured by weight; the unit of scale is referred to as carat abbreviated ‘CT’. One carat is equal to one fifth of a gram. Each carat can be divided into 100 points. Within the industry, diamonds are also sold as units per carat. That is, if there are 10 diamonds and they each weight 10 points then the total carat weight is one carat. Hence known as 10 per carat. A .01ct is also known as a 100 per carat, and .02 is a 50 per carat.