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Diamond Selection Guide


Diamond is the rarest mineral on Earth. But not all diamonds are equally valuable, and size is far from the only indicator of quality. Our guide to buying diamond jewellery makes it easy to find your way around, whether you're choosing an engagement ring, diamond earrings or a necklace. ALO Jewelry only uses diamonds that meet the highest jewelry standards. We will issue a certificate for each piece of diamond jewelry, verifying authenticity and detailing the characteristics and quality. The characteristics and quality of each diamond is assessed by experts using four basic criteria - carat weight, color, clarity and cut.


Weight (Carat)

The weight of a diamond, given in carats (1 carat = 0.2 g), is one of the most important characteristics that determine its price. But it is far from the only one: two diamonds of the same size can differ significantly in price if they have different clarity, colour and cut. Thus, a smaller but better quality stone can be more beautiful than a larger diamond with significant flaws.




Colour is assessed by comparison with sample stones under standardised artificial light, which is the same as daylight in the northern hemisphere. For white diamonds, a colourless diamond is considered perfect. This is because it is the diamond that can best break down the incident light and create the iridescent flashes called fire. Most natural diamonds, however, contain discoloration caused by tiny impurities inside the stone.



D premium white +
E premium white
F very white +
G very white
H white
I J lightly tinted white
K L tinted white
M N-O P-R S-Z slightly yellowish - almost yellow


It is very rare to find a perfect diamond. Almost all diamonds contain minor imperfections, so-called inclusions or trace occurrences of other minerals. A diamond is called "flawless" if, after examination by an experienced expert, it contains no internal "impurities" when magnified ten times under a loupe. Other clarity grades are determined by the size, position, brightness and number of internal elements. The quality grades on the scale (denoted by the letter p for piqué) indicate defects that may be visible to the naked eye of an experienced examiner.




The blemishes are not visible to the naked eye.


The blemishes are visible at tenfold magnification and exceptionally may be visible to the naked eye.
A diamond of acceptable quality.

I1, I2 (P1, P2) - INCLUDED (PIQUÉ)

A diamond of inferior quality. Flaws that can be seen with the naked eye of an experienced connoisseur.



Why is grinding so important? Because it is what determines how the diamond will reflect light. The better the cut, the more the diamond sparkles. A perfectly cut diamond sparkles all over and, in addition, we can observe iridescent flashes called fire, which are caused by the mutual reflection of light by the individual faces. In contrast, a poorly cut stone is cloudy, glassy, and shows areas that appear darker because they do not reflect light. The cut therefore affects both the visual aspect of the diamond and its value.




The most common diamond shapes: