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Diamonds amongst gemstones are rare. The finding of single stone can be the result of amazing chance finding, or the result of a determined effort by perhaps hundreds of people and resources. Diamonds can be found recovered at or beneath the surface of the earth.

A diamond is rare because for example out of 100% of diamonds that are discovered, 75% is of industrial quality diamonds the remainder 25% are gem quality. And even in those differing qualities exist.

Qualities of diamonds

Gemstones are minerals that require three basic qualities to be used in valuable jewellery:

  • Durability
  • Beauty
  • Rarity

This is perfect example of the qualities of a carefully chosen diamond. A diamond owes its remarkable beauty to the following factors:

  • Brilliancy
  • Dispersion (or Fire)
  • Scintillation (or Sparkle)
  • Lustre

The four Cs

The diamond is always associated with the Four C's these being: Clarity, Cut, Carat and colour. However there is a fifth C, which overlooks all these, and Will endeavour to make the customer feel content and happy with product they receive. The fifth C determines everything, COST!

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This refers to how clean the stone is of inclusions. Diamond graders evaluate a diamond on a scale of inclusions from flawless to imperfect inclusions.

A diamond is said to be clean if no inclusions could be discovered with a 10X Loupe (a lens which is used by diamond graders and traders). Inclusions can be minute in traces of either mineral trapped during the crystallisation process. These natural characteristics called inclusions are often described as natures finger prints.

The flaws inside the stone are called inclusion and the external flaws are called blemishes.

When purchasing a diamond there some important factors to keep in mind when it comes to clarity.

  • Number of inclusions
  • Size of inclusions
  • Prosecution of inclusions
  • Colour of inclusions (black, white and transparent etc)

Glossary of internal inclusions:

  • Bearding
  • Feathers
  • Included crystals
  • Internal twining
  • Bubbles

Glossary of external inclusions or blemishes:

  • Polishing lines
  • Scratch
  • Nicks
  • Pit
  • Natural
  • Abrasion
  • Extra facet
  • External twinning
  • Rough Girdle

A universal agreed standard by GIA and HRD

(Click image to see large view)

diagram showing degrees of clarity

Flawless: Free from internal and external flaws and inclusions
IF: - Internally flawless: Free from internal inclusions, only possesses external Characteristics.
VVS1 - VVS2: Very Very small inclusions extremely hard to find with a 10X loupe. (Minute inclusions)
VS 1 - VS 2: Small inclusions hardly to be found with a 10x loupe.
SI - SI 2: Small inclusions found easily with 10X loupe
PI: inclusions easily visible with a 10x loupe but not with a naked eye.
P2: Large and numerous inclusions easily visible to the naked eye
P3: Large and numerous inclusions very easily visible to the naked eye, which also reduce the brilliancy of the diamond.

Since it is difficult to find a diamond that has no inclusions - the closer to flawless the greater the value

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The closer a diamond is to having no colour the more valuable it becomes, however diamonds may seem colourless but shade difference do exist. When a diamond is formed in the earth due to extreme temperature and pressure traces of elements such as nitrogen and boron could be incorporated into the diamonds atomic structure. It is there traces that give diamonds colour or lack of it.

Diamonds with no colour are very rare; smartly diamonds with very strong colour are also very rare and are called fancies. Red, pink blue are highly prized.

Most gem-quality diamonds appear to be colourless, but usually they do have at least a hint of colour, this is normally yellow or brown due to traces of nitrogen:

(click image for larger view)

diagram showing degrees of colour

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All factors of the 4 C's are important, however it is the Cut the gives a diamond the allure and attracts the eye. If a diamond were not well cut it would lack lustre and have no appeal even if it was a D flawless!

The precision cutting of the diamond, dictates the amount of light it will reflect and refract. The better a diamond has been cut, increases the brilliance, sparkle or fire of the stone.

diagram showing various cuts

A well-cut diamond with good proportions reflects the light coming in to the stone from facet to facet then it is dispersed through the crown (top) of the diamond.

If the diamond has been cut to shallow the light will escape through the opposite side of the pavilion (or the bottom of the stone). So it is not reflected.

diagram showing refraction of light

It is universally agreed that quality of the cut and the final polish of the stone unlocks the hidden beauty of the stone. It is a combination of the unique optical properties, the high refractive index as well as the dispersion of colour.

A brilliantly cut diamond shows these important properties in a remarkable way. Maximum Brilliance is the interlaced harmony of lustre, internal reflection, dispersion and scintillation.

Lustre: The total amount of light reflected in the stone

Internal reflection: The same amount of light that enters through the crown is back through the crown

Dispersion: Splitting or scattering of the light into the spectral colours is dispersion. It Evokes the life or fire in a brilliant cut stone

Scintillation: The terms used for sparkle of the rays, when a stone is moved or when the light source changes.

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(click for larger image)

diagram showing selection of carat sizes

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