The 4Cs – cut, colour, clarity and carat – are crucial for you to consider when buying a diamond. As each of those determine the value of the gem. A change in one or all, can lead to an increase or decrease in value and price.
Or the shape of the diamond. Round-brilliant is the most popular and highly desirable for the brilliance (more on this later). Every other cut that is not round is a fancy shape.
Or rather, lack of colour, for white diamonds. Measured on a scale from D to Z. With D, E and F the top 3.
How (if any) many inclusions or blemishes, visible under x10 magnification. We use a loupe to determine the amount of inclusions. Taking into account size, nature, position, colour and number of inclusions. How many there are, how they came about (nature) are determinants of value. All else being equal, the higher the clarity the higher the value. Clarity ranges from flawless (IF) at the top end, very slightly included (VS1) in the middle, to I (included) at the lower end.
Or the weight. 1 carat = 0.20 grams.