MAIN CRITERIA FOR CHOOSING A DIAMOND

If you have decided to invest in diamonds, it is necessary to know the criteria based on which diamonds are selected. The evaluation is carried out by internationally recognized gemological laboratories. 

These criteria determine the value and quality of a diamond, there are 4 of them and they are referred to as the 4Cs:

CLARITY, COLOR, CUT, CARAT.

When choosing a diamond, it is necessary to clarify whether the diamond will be part of a piece of jewelry that will please your eye and at the same time be an investment, or you decide to buy an investment diamond that is never part of a piece of jewelry.

Diamond evaluation criteria

Diamond clarity - CLARITY

The clarity of a diamond refers to the degree of internal defects. These can be crystals of foreign material, uncrystallized carbon or structural defects such as small cracks that can cause a whitish tinge to the diamond. The most valuable diamonds are completely pure and ideally crystallized. However, such diamonds are rarely found. Only about 20 percent of mined diamonds have sufficient clarity and can be used in jewelry. The remaining 80 percent are used industrially as cutting tools or abrasives. Although inclusions reduce the price of a diamond, they also serve as a diagnostic tool. We can tell from them that the stone is genuine (of natural origin). External characteristics such as scratches, etc., are not included in the clarity assessment.

Inclusions can be found in almost all rough diamonds, most commonly they are:

• crystalline inclusions - crystals of other minerals or additional diamonds that were present during the formation of the diamond
• cracks, fissures, feathers
• clouds

How diamond clarity is determined

Diamond clarity is determined by gemological laboratories based on carefully compiled rules. The scale of the Gemological Institute of America (GIA) is certainly one of the best known and most reliable. When evaluating clarity, you may also encounter the AGSL scale, which works with grades 0-10, where 0 denotes a grade without impurities.

The clear GIA table shows different levels of diamond clarity img.

Diamond clarity is examined by an experienced expert using a special 10x magnifying aplanatic achromatic loupe, in normal light. The location, size and type of inclusions found are always precisely stated in the diamond certificate. A flawless diamond is considered to be one that has no visible flaws even at ten times magnification. The clarity of a diamond can be additionally improved, for example, by laser treatment, but the intervention must be clearly described in the certificate, e.g. "laser drilled". The clarity classification then corresponds to the clarity of the stone after treatment.

Diamond color - COLOR

The color of diamonds in nature is very diverse. If a diamond is formed under perfect conditions, it is colorless. In nature, we can encounter a whole range of colors. From colorless diamonds, through slightly yellowish, to orange, pink, purple, blue or even extremely rare red stones. Common tints - most stones occur in color tones ranging from slightly yellowish to brownish-yellow. This tint reduces the price of the stone. Yellowish diamonds are classified into the "Cape" or "Cape series" group and are cheaper. The color of a diamond is assessed according to the GIA (Gemological Institute of America) color scale, which divides diamonds according to colors using letters of the alphabet from D to Z. The letter D denotes completely colorless diamonds (first-class white+) and the most tinted by the letter Z, see the GIA color scale table below.

Colorlessness in diamonds is highly valued. Completely colorless diamonds are the most valuable of common diamonds.

Clear GIA color scale table img.

Fancy diamonds - colored diamonds 

The more colorless a diamond is, the more expensive it is. The exception are the so-called fancy diamonds, natural colored diamonds. The GIA scale does not apply to them and their price can exceed even perfectly colorless diamonds. The color is assessed using a comparison set of stones, the so-called master stones, under a lamp imitating daylight. An electronic colorimeter is also used to determine the color of the stone. Although technical equipment is developing rapidly, no commercially available colorimeter has yet replaced the human eye. 

 fancy diamonds - colored diamonds img.

Diamond cut - CUT

Diamond cutting is a jewelry activity in which rough diamonds are cut to create gemstones that can be used in jewelry. A rough diamond only gains its beauty after being cut. For larger and more expensive stones, cutting is done by hand, while for smaller stones, machine cutting is mostly used today. 

The quality of diamond cuts is evaluated based on proportions, surface finish and symmetry.

According to the international scale, there are five grades of cut quality: 

Excellent/Ideal cut, Very good, Good, Fair and the worst Poor.  

 The following are also evaluated for the cut:

• amount of reflected white light - brilliance
• light dispersion coming from the cut stone - fire 
• degree of color play when moving the stone or head - sparkle

Diamond cuts

• Brilliant - round cut, the most well-known and widespread cut with 57 facets, which are cut to precisely defined proportions.
• Princess - a four-sided cut with sharp corners, sometimes also three-sided.
• Emerald - emerald cut, typically rectangular in shape with truncated corners and a wide surface that resembles a staircase when viewed from above.
• Asscher - known not only for its exceptional shine but also for the typical and beautiful optical illusion known as the "hall of mirrors". This shape is very often confused with the square emerald shape, whose shape is almost identical, and there are often disagreements about their exact differences.
• Pear - pear-shaped (teardrop) shape
• Radiant - square shape with distinctive "trimmed" corners.
• Oval - rounded elongated shape.
• Cushion - rectangular or square shape with typical rounded corners, resembling a cushion, hence its name "cushion".
• Heart - the heart shape is most often composed of 56 to 58 facets.
• Marquise - the shape of the "marquise" gemstone cut resembles a ship's hull with its two-pointed design.
• Triangle - triangle shape
• Baguette - rectangle

diamond cuts img.:

Diamond weight - CARAT 

• The weight of a diamond is given in carats, with the abbreviation ct. This is a different carat than for gold, which is a unit of purity and has the abbreviation kt.
• The metric carat (Carat) is defined as 0.2 g and is denoted ct.
• A diamond weighing 1 g therefore has 5 ct or 1 ct = 200mg = 1/5 gram.
• Diamonds in commonly sold jewelry usually have a weight in hundredths, tenths to units of carats.

Weight determination

The weight of diamonds is determined on very precise diamond scales - today most often on electronic carat scales. However, given the clearly defined parameters of the brilliant cut, we can also determine it by measuring the brilliant.

Weight and Price

The price of a diamond does not increase in proportion to its weight. This is because large diamonds are rare and therefore more valuable. A 2-carat diamond is therefore more expensive than two one-carat diamonds with otherwise identical properties. The largest diamonds found have thousands of carats.

Everything about diamonds in a nutshell - table for printing JPG