Chemically, a Diamond is an Allotrope (one of the varying forms of Carbon). Extremely hard and tough, with a high dispersion of light, they polish to a beautiful lustre. With increased technology in cutting techniques and some healthy marketing, Diamonds are, without doubt, the most popular choice of gemstone in the world.

The name derives from the ancient Greek ‘adamas‘meaning ‘invincible’. It is the hardest Natural substance known to man. For this reason, Diamonds are also sought for numerous other uses such as scalpels, drill bits and engraving tools. Only 20% of the World’s mined Diamonds make it to the jewellers workbench.

Diamonds have come a long way over the centuries in respect of methods of cut, enhancement and synthesis.

Diamonds are graded using the “Four C’s” system and price per carat depends on the following criteria:


Carat is the unit of weight for all gemstones. One carat is divided into 100 “points”. Therefore, a Diamond measuring 75 points is equal to 3/4 carat in weight, or 0.75ct. The word “carat” comes from the seed of the carob tree pod, which is found in tropical climates. These seeds were used to weigh precious gems up until the early parts of the last century.

High carat Diamonds often appear to be brighter or more brilliant than smaller ones due to the prism effect of light travelling over larger distances.

If combined well with the other 3 C’s, the larger the Diamond, the stronger the effect on the value of the stone, and so larger white Diamonds relatively free of inclusions will cost more per carat than similar stones of a smaller weight.


Ideally, a white Diamond should have no colour at all. Increasing degrees of body colour are measured on a scale ranging from (D), no colour to (L), colour becomes predominant in the stone. Grading continues to (Z) however, stones between grades M-Z are more commonly referred to as Champagne, Cognac or Fancies. Grading is done by comparing the Diamond to be graded against a set of “master stones” calibrated to the spectrum of the Northern Hemisphere, under either artificial or natural light. A machine called the “Colorimeter” can be used for colour grading although there is no substitute for the trained human eye.


A Diamond’s clarity is determined by the number, nature, position, size and colour of internal characteristics called “inclusions”. These inclusions are nature’s ‘fingerprints’ and each Diamond has its own unique pattern. Diamonds are pure carbon, however, during crystallization other minerals nearby, or even other bits of carbon forming more quickly may have become trapped within the cooling mass. These show themselves as the various characteristics, which make up the clarity of a Diamond (included crystals, feathers, clouds etc). Clarity is measured on a scale ranging from flawless to heavily included (pique). The clarity of a diamond is graded by using 10X magnification by an experienced grader. The final clarity grade is usually determined by how easy the inclusions and blemishes are for the grader to see.

Clarity grading ranges from:

  • Loupe Clean (FL/IF)
  • Very Very Slight inclusions (VVS1, VVS2)
  • Very Slight Inclusions (VS1, VS2)
  • Slight Inclusions (SI1, SI2)
  • Included (I1, I2, I3)
  • Free from Inclusions
  • Inclusions very hard to find with a Loupe
  • Inclusions hard to see with a Loupe
  • Inclusions easily discernible with a Loupe
  • Inclusions can be seen with the naked eye.


Cut, sometimes the forgotten “C”, ensures that a given stone has maximum brilliance and sparkle, which would not be the case were the stone cut for weight alone.

The facets of a Diamond are placed to maximise the reflection of light through the stone. In an ideal situation, light entering through the top of the Diamond is reflected around the facets and returned to the eye. Where Diamonds are poorly cut, the light doesn’t make it back to eye, but simply gets ‘lost’ out of the side or base of the stone giving a lack lustre appeal. Good cutting can make an average Diamond light up. Certified Diamonds will generally have the cut of the Diamond broken down into cut, symmetry and  polish.

Cut also refers to the shape of a Diamond: round, emerald, heart, marquise or pear for example. This generally is a matter of personal taste and fashion trends. However, each cut has its own “perfect’ cut proportions that it is graded against.

Today the purchase of Diamonds is a more complicated procedure. Modern technology has brought in techniques that although may appear to enhance your Diamond, are required by law to be disclosed at point of sale. Unfortunately, with the Internet, many unsuspecting buyers purchase Diamonds that are not as presented. This is why, when purchasing a larger Diamond, it is recommended you look for what is frequently known as the ‘Fifth C’: Certification. By purchasing a Diamond with a Certificate from an Internationally recognised Grading house, such as GIA, HRD, IGI, and EGL, you are assured that your Diamond has been checked for any treatments and is certified as natural and un-enhanced. There is a significant variance in price from untreated stones, and you need to understand what you are taking on with a treated stone. For example, a ‘Fracture filled’ Diamond needs to be disclosed to your jeweller if they are going to polish, resize or in general work on it, as this treatment will be ‘undone’ in normal manufacturing processes. This is just one treatment currently occurring. There is no better advice we can give, than to discuss your Diamond needs with a professional Jeweller, who can walk you through the options.

Now being promoted as the “5th C” , Certificates are becoming more prominent in the marketplace. Certificates or Grading reports should preferably be prepared by an independent Grading Laboratory who has no financial interest in the sale of the stone they are grading, such as the following Internationally recognised laboratories.:

  • Gemmological Institute of America (GIA)
  • Antwerp Diamond High Council (HRD)
  • European Gemmological Laboratory (EGL)
  • International Gemmological Institute (IGI)

These reports are an assessment of the 4 C’s characteristics of the Diamond and should have no indication of value.