Clarity is evaluated under good lighting by a specialist using a 10X magnification loupe. Diamonds with no discernable inclusions or blemishes interfering with the passage of light through the diamond receive the grade FL (flawless), with 11 grades following, depending on the number and size of inclusions. TASAKI BRIDAL uses only diamonds achieving a grade of VS2 or above. TASAKI has, moreover, set its own clarity grading system (appraisal standards), and diamonds on the borderline between two grades are judged strictly at the lower grade. This ensures that our grading standards remain reliable.

A carat is a unit used in measuring the weight of a diamond, and is equivalent to 0.2g. It is generally believed that the more carats a diamond has the more expensive it will be. However, the value of a diamond is not necessarily determined based only on its weight. A high-quality, beautiful diamond is one in which all the 4 C’s combined—cut, clarity, carat, and colour—are outstanding. For example, if there were two round brilliant cut diamonds of the same diameter and one had been cut with a thick girdle, that diamond would have at least 10 percent more carats. However, a surprising amount of brilliance would have been lost, and that is why TASAKI cuts diamonds according to its own ideal proportions.

The closer a diamond is to colourless and totally transparent, the greater its rarity value. Colour is rated according to 23 grades from the highest grade of D (colourless and totally transparent) to Z, depending on the yellowness of the stone. Only diamonds of grade H (close to colourless) or above are accepted for the TASAKI BRIDAL range. Furthermore, some diamonds have strong fluorescent properties that make them glow when they absorb ultraviolet light. However, they appear cloudy under natural light, so TASAKI checks for fluorescence at the rough diamond stage, and uses only diamonds that have little or no fluorescence.