Cut is the most important factor to a diamond’s overall beauty. Most gemologists consider cut the most important diamond characteristic because even if a diamond has perfect color and clarity, a diamond with a poor cut will have dulled brilliance.
The cut of a diamond determines its brilliance. The finer the cut, the better proportions which yields a higher degree of brilliance or sparkle, which is basically how light travels within the diamond, and how it exits in the form of brilliance.
Diamonds with the highest cut grades and best proportions cost more, not only because they are rarer, but also because of the skill and experience needed by the diamond cutter to produce such a beautiful stone. In addition, far more time is required to produce a well-cut stone. Cut is not to be confused with shape, diamond shapes are very different, with unique characteristics which determine the quality for each shape. Diamond shapes include round, marquise, oval, pear, princess, emerald, heart, cushion and asscher.
The human eye tends to detect sparkle (light performance) before color. This is why color is generally considered the second-most important characteristic of buying a diamond, after cut.
Diamond color is graded on a alphabet color scale starting with D and going down through Z.
- D color grade – colorless – the highest color grade
- E – F color grades – colorless slight color detected by an expert gemologist
- G – H color grades – near colorless, color noticeable when compared to diamonds of a higher grade
- I – J color grades – near colorless, color noticeable and detectable, starting to show yellow tints
- K – M color grades – noticeable color, pale yellow to strong yellow
- N – Z color grades – noticeable color strong yellow to brown
As diamond size increases, color becomes more noticeable. This is especially important to keep in mind if purchasing a larger diamond, such as, two carats or greater. The visible difference between diamonds of one color grade, for example G to H or I to J, is so minor it may be difficult to detect with an untrained eye. The cost savings, however, can be significant.
The type of metal in which a diamond is set can sometimes complement its color. We recommend setting diamonds graded I or J in yellow gold. White gold or platinum best complement diamonds with a color grade of D through H.
Diamonds that are absolutely clear are the most sought-after and therefore the most expensive. But many diamonds have inclusions (flaws) — scratches, trace minerals or other tiny characteristics that can detract from the pure beauty of the diamond. The Gemological Institute of America has a detailed lettering system of rules and standards to summarize the number, location, size, and type of inclusions present in a diamond, graded as follows:
- FL, IF – flawless, internally flawless, no internal or external flaws – very rare
- VVS1, VVS2 – very, very slightly included, very difficult to see under 10x magnification
- VS1, VS2 – very slightly included, inclusions not visible to naked eye, but slightly visible under 10x magnification
- SI1, SI2 – Inclusions are visible under 10x magnification, and may be visible with the naked eye
- I1, I2, I3 – visibly included to the naked eye
Carat is specifically a measure of a diamond’s weight. In weight comparisons 5 carats equals one gram and in carat measurements one carat equals 100 points, hence a 1/2 carat is also 50 points or .50 carats. Although carat weight alone will not give you an accurate view of a diamond’s size, but should be considered in conjunction with the measure in millimeters across the top of a diamond, and the diamond’s cut grade. When a diamond is well cut, the light reflected out of the top more efficiently and makes it appear larger.