When buying a diamond the the important aspects are broken down into four sections known as the four C’s.
The four C’s are Colour, Cut, Clarity and Carat weight.
The first of these are Colour , this is graded by eye and is probably the most difficult to determine in isolation. Colour runs from D through to Z with the most sought after stones falling into the F/G range as these are in the rare white range without the additional cost of higher collection colours in the D/E range.
Next is Clarity this is based on the number and size of Inclusions in your diamond. Range is from Flawless to I3. Most sought after would be in the VS2/SI1 range.
Cut is based on how well your diamond is cut and not on the shape of your diamond.
Each shape has its own set of parameters that are best for that shape. Cut grades for round stones are based on Cut quality, Symmetry and Polish. You should look for Excellent or Very good across all three.
The fourth C is Carat weight, this is based on the overall weight of the stone ( it is not the diameter size of the stone).
100 points (or Cents) equal 1 carat.
A .60ct diamond = 60 points weight.
The point price of the diamond increases as the diamond weight increases.
A .20ct diamond might costs €400 euro ( €20 euro per point or €2000 euro per Carat)
A .50ct diamond might cost €2500 euro ( €50 euro per point or €5000 euro per Carat)