When it comes to choosing a diamond, there are many varying characteristics and quality factors that can determine the brilliance, sparkle and overall aesthetic impact of the stone. At Concept26 we work only with the highest quality diamonds and pride ourselves in providing genuine, accurate information on what to look for in the ideal diamond. Summarized here in our Diamond Guide are the most important details we suggest to keep in mind when looking for the perfect diamond.All of our diamonds are ethically sourced under the Kimberly Process Certification and have been since our inception.


When choosing a diamond, the first decision to be made is what shape you prefer. Diamonds come in a wide range of shapes, with the most popular being a round brilliant cut – which most people will recognise as the classic shape for a solitaire style ring. Other common shapes include oval cut, emerald cut, pear cut, marquise cut, cushion cut, asscher cut, princess cut and trilliant or trillion cut, along with other more unusual shapes, each with their own unique qualities to suit different styles and preferences.


The cut of a diamond is not to be confused with its shape – this term actually refers to the quality of how it’s been cut, which is important in ensuring the maximum return of light back to the viewer’s eye and is the factor that fuels a diamond’s fire, sparkle and brilliance. Precise workmanship is required to cut a diamond so that its proportions, symmetry, and polish maximize its beauty. Cut grades are unique to round brilliant cut diamonds only, and do not apply to any other shape. The quality of cut is crucial to the diamond’s value, and at Koi Jewels we work only with excellent cut round diamonds. For fancy shape diamonds, which is the term applied to all other shapes outside of round, it is the polish and symmetry grades which determine the quality of the cut of the stone. A high quality fancy cut diamond will present very good to excellent polish and symmetry, whereas a round diamond should have excellent grading for both categories.


Color refers to the natural body color of a diamond and not to the reflection of spectral colors that flash when a diamond moves. Most diamonds naturally exhibit slight hints of yellow, brown, or grey, and so the less color a diamond exhibits, the higher it’s value due to the rarity of colorless material. Color quality is graded via an alphabetical system, ranging from D (colorless) to Z (light yellow). Each letter grade represents a range of color and is a measure of how noticeable that color is.

The clarity of a diamond refers to the presence of inclusions within the stone. Practically all diamonds contain naturally occurring internal inclusions. These are generally either foreign materials, such as carbon or other minerals which were trapped inside the diamond as it has grown around them, or clear inclusions such as fractures and tiny imperfections in the structure of the diamond. The size, nature, location and amount of inclusions determine a diamond’s clarity grade and affect its value. The diamonds that we source at Koi Jewels are strictly SI1 clarity and above, and we encourage prioritizing a stone with no eye-visible inclusions to guarantee the best sparkle and fire.


Carat is the measurement of how much a diamond weighs. A metric ‘carat’ is defined as 200 milligrams. All else being equal, diamond price increases with carat weight, because larger diamonds are more rare and more desirable. However, two diamonds of equal carat weight can have very different values (and price) depending on three other factors of the 4cs: Color, clarity and cut.

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