The Selection

  • If you are purchasing a diamond generally the main factor considered is the size or carat weight. The “Carat” is a measure of weight of a diamond and derives from the weight of a “Carob” seed, which surprisingly enough is generally uniform.
  • The size or Carat weight is likely to be the biggest determining factor of the price.
  • Following on from the size there are two factors which have a bearing on which diamond you might like to choose and those are colour and clarity, probably in that order. Both equally have a bearing on price.
  • Colour in white diamonds is a classification which strangely enough begins at “D colour” and in the top colours go to “J or K colour”, which have a slight hint of yellow. The yellow colour in diamond derives from the presence of Nitrogen atoms in the Carbon crystal lattice and the greater the presence of Nitrogen the yellower the diamond becomes.
  • Lastly although probably the most important characteristic of the diamond is its cut, since this will influence the light properties of the diamond and the amount of ‘radiance’, ’fire’ and ‘sparkle’ emitted by the diamond. Hence, the most significant factor in its appeal. 


  • Size is usually one of the first considerations in choosing a diamond in that the buyer usually has a mental picture of how big they would like the diamond to be
  • And clearly the bigger the diamond the more expensive it is going to be so this is usually determined by the buyer’s budget
  • Other factors include the setting of the particular diamond and if it is to be incorporated into a ring, then the size of the fingers of the wearer will be crucial
  • Size can vary from country to country of course and it is more fashionable in the USA for buyers to go for larger diamonds than in Japan, where the preference is more for delicacy and refinement


  • Clarity is a measure of how ‘clean’ the diamond is internally which varies from ‘Loupe Clean’ to ‘Pique’
  • The internal characteristics of the natural diamond do give it its character, however, and these ‘experiences’ the diamond has undergone in its formation make for the individuality of the stone
  • Some internal features include traces of foreign particles or crystals and some include ‘gletches’ or ‘feathers’ or the like
  • It is important that internal features may impact on the emission of light or the ability of light to reflect throughout the stone and so are an important feature in choosing a diamond which meets the buyer’s satisfaction
  • Clarity will naturally affect the price and the clarities are classified from most expensive FL (Flawless) through VVS (Very Very Small inclusions), VS (Very Small) to I (included), being far less expensive


  • A little further explanation on “Colour” is required, since diamonds come in many different colours, albeit the most common colour is white. 
  • In white diamonds, the colour varies from D through J and K all the way to Z in fact, where the quantity of Nitrogen is assumed to be detrimental to the ‘white’ colour. 
  • However, very high quantities of Nitrogen in the diamond result in the diamond moving into “Fancy yellow” territory, the higher the concentration the higher then the price once more becomes. 
  • All “Fancy” colours, whether they be yellow, blue, pink, orange, brown, grey or red range from “Fancy Light” through “Fancy Intense” to “Vivid”. Vivid colours becomes highly sought after and much higher priced than the “Fancy Light” or “Fancy Intense” colours.


  • Perhaps by far the most important criteria after the buyer has determined the size is the Cut which will govern the the light properties of the cut diamond and hence:
        • Brilliance
        • Fire 
        • Sparkle
  • The proportions of the diamond are therefore a critical factor in determining how the light will reflect internally around the diamond and ultimately emitted to the viewer
  • Too shallow a cut of diamond will result in a lot of light escaping from the stone underneath and not being reflected through the table again, sometimes causing a ‘fish eye’ effect.
  • Likewise, too tall a cut will lead to a lot of light disappearing out of the sides of the diamond resulting in it having less brilliance

Cullinan Character

On the gravestone of Sir Thomas Major Cullinan stand the words: “He was Brave of Heart, Magnanimous, Courtly, Courageous”

Qualities, it could be said, useful for the selection of the ultimate CULLINAN DIAMONDS™ Engagement Ring!