Diamonds - The Four 'C's'

Carat

The weight of a diamond is measured in carats. One carat is divided into 100 "points" so that a diamond of 25 points is described as a quarter of a carat or 0.25 carats.

(Charts shows actual size of diamonds)

The larger the diamond (and therefore the rarer) the more expensive per carat it will be. For example, a 1ct diamond costs much more than two 1/2ct diamonds and one 30 point diamond costs much more than 30 one point diamonds.

The carat measurement of a diamond is actually a measurement of the diamond's weight rather than its size or diameter. This is important to remember as depending upon the proportions of the cut of the diamond, some diamonds may appear to have a larger top surface area than an ideal cut diamond but the diamonds may be of the same carat weight. Diamonds are sometimes cut in shallow proportions to make a diamond look bigger but this sacrifices the brilliance and life of the diamond and make them less valuable.

Do not confuse carat with karat. Carat refers to stone weight while karat refers to fineness of gold.

Colour

Diamonds come in a range of colours, from totally colourless to tinted. The most rare and valuable colour is the highest and whitest, colour D, a lower colour that isn't as valuable is still just as good in quality as a higher colour if the clarity and cut is the same. Some natural fancy coloured diamonds, eg: intense yellow, pink, blue, red, etc. can be much more valuable than the whitest diamonds. Natural fancy colours are not classed as low colours. The lowest colour is a personal choice and the lowest colour to stay true white is colour H. Colour I is a commercial white, colour J is slightly tinted but can still look white or whitish. I and J colours may still be OK for white diamond shoppers. People who demand the finer whites should start looking from colour G and above.

Clarity

Diamonds can have nil, slight, medium, strong or very strong fluorescence. Fluorescence when strong and very strong can make colour of the diamond appear different under certain types of lighting. Some people like this but most prefer nil and no higher than medium. Blue Fluorescence will make colour look whiter, especially if it's a low colour.

A yellow Fluorescence will make Colour look lower, especially if it's a high Colour. Do not take Fluorescence into account if graded nil , slight and in most cases medium. Negligible Fluorescence usually cannot be seen with eye and is of no consequence. Fluorescence is not necessarily bad. In some cases it can be an advantage, eg: Budget restricts that you buy a low Colour diamond, but you prefer a higher Colour. Strong and very strong blue Fluorescence will make diamond appear whiter.

Most diamonds contain inclusions that may be visible with naked eye or only visible under 10x magnification. SI2 and higher is not visible with the naked eye under normal grading rules. SI3 is a split, a diamond that was too good to be a I1 and not good enough to be a true SI2, however usually SI3 stones are graded either SI2 or I1 as most laboratories do not grade SI3.

The lowest Clarity recommended is I1. I2 and I3 have heavy inclusions - I4 and I5 are classed as reject stones.

The highest Clarity is FL = Flawless, IF = Internally flawless with minor surface blemishes. (Other term used with some labs, LC = Loupe clean, meaning: Flawless or Internally Flawless).

There are other features in some diamond that have a role in the clarity, good examples are cloud or graining in the diamond.

Example: D IF with a faint cloud was downgraded to D VS2. As long as the Clarity is downgraded by the grading laboratory to VS2 then it's OK since it's sale value was a D VS2 which is much less valuable than a D IF.

Diamond grading certificates will indicate all internal features (inclusions, etc) with red markings and all external features with green markings. External features are usually not part of Clarity grading.

Note: V V S 1 is slightly higher clarity than V V S 2, 1 is always higher than 2 in each clarity grade. (both terms are used but have the same meaning). I = Imperfect and P = Pique

Cut

While nature determines a diamond's colour, clarity and carat weight, the hand of a master craftsman is needed to release its fire and beauty. The cut gives each diamond its unique sparkle and brilliance by allowing the maximum amount of light to enter and reflect back out of the diamond.

The carat measurement of a diamond is actually a measurement of the diamond's weight rather than its size or diameter. This is important to remember as depending upon the proportions of the cut of the diamond, some diamonds may appear to have a larger top surface area than an ideal cut diamond but the diamonds may be of the same carat weight. Diamonds are sometimes cut in shallow proportions to make a diamond look bigger but this sacrifices the brilliance and life of the diamond.

Diamonds may be cut in different shapes with the most common shapes being round (brilliant cut) and what are referred to as fancy cut diamonds including marquise, oval, pear shape, baguette and princess (square)cuts.