Understanding the 4Cs of Diamonds

Cut

Diamond cut is crucial to a diamond's appearance and value; it is the most complex and technically demanding standard among the 4Cs. Many people mistake diamond cut for diamond shape (round, heart, oval, marquise, pear). In reality, a diamond's cut grade is determined by how its facets interact with light. The assessment of cut includes "cut proportions," "symmetry," and "polish." An excellent cut results in a high refractive index, giving the diamond a brilliant radiance. Different diamond grading institutions may have different cut classification systems. GIA classifies cut into five grades: Excellent (EX): Only slight facet irregularities or hard-to-detect polish lines, which do not affect the diamond's light reflection at all. It features even light/dark patterns and extremely colorful fire, with polish or symmetry being excellent, or one being excellent and the other very good. Very Good (VG): Only slight polish lines or inconspicuous surface features, not affecting the diamond's reflective capability. It features minimal fragmented light/dark areas, good fire, and polish or symmetry being very good, or one being excellent. Good (G): Some transparent polish lines visible from the face-up view, many small surface features, facet asymmetry or crown/pavilion proportion deviations, with larger dark areas visible from the top. Fair (F): Visible transparent or hazy polish lines, obvious surface features or proportion deviations, with poor light/dark contrast and an overall dull appearance. Poor: Surface features that reduce the diamond's transparency and obvious symmetry deviations. IGI classifies cut into six grades, with "Ideal" being the top grade above Excellent (EX). A diamond's cut directly affects its:

• Brightness: The white light reflected from inside and outside the diamond
• Fire: The scattering of white light into the colors of the rainbow
• Scintillation: The total amount of sparkle produced by a diamond, which is related to the number of facets; more facets lead to stronger scintillation

Recommended reading:

• Myths about Lab-Grown Diamonds vs. Natural Diamonds
• Understanding How Lab-Grown Diamonds are Produced
• Why do Lab-Grown Diamonds Hold Value?

Clarity

Diamond clarity refers to the assessment of surface blemishes or internal characteristics. Foreign crystals or diamond crystals trapped during formation, structural defects created during growth, or surface flaws created during cutting and polishing are all referred to as such. Generally, the clarity characteristics of gem-quality diamonds are invisible to the naked eye. Under 10x magnification, the clarity grade is determined by the size, number, position, nature, and relief of these characteristics.

• The diamond clarity standard is divided into 6 categories and 11 grades.
• Flawless (FL): No inclusions or surface characteristics are visible under 10x magnification.
• Internally Flawless (IF): No inclusions visible under 10x magnification.
• Very, Very Slightly Included (VVS1 and VVS2): Extremely small inclusions visible under 10x magnification, difficult even for expert graders to see.
• Very Slightly Included (VS1 and VS2): Minor inclusions visible under 10x magnification.
• Slightly Included (SI1 and SI2): Inclusions are visible under 10x magnification.
• Included (I1, I2, and I3): Inclusions may affect transparency and brilliance and are obvious under 10x magnification.
• The higher the clarity, the higher the value of the diamond.

Recommended reading:

• Authoritative Recognition of Lab-Grown Diamonds
• The Big Difference Between Real Diamonds and Imitations
• Major Diamond Grading Institutions and Certificates

Color

The diamond color grading standard is based on the lack of color. A diamond without chemical impurities and with perfect structure is like a drop of pure water, devoid of color, and holds higher value. Completely colorless diamonds are rare; most exhibit shades of brown or pale yellow. Color grades range from "D" to "Z," with subtle distinctions between them. D, E, and F are classified as Colorless, while G, H, and I are classified as Near Colorless. In practice, it is difficult to perceive the differences between D, E, and F with the naked eye, although differences become apparent when two diamonds of significantly different grades are placed side-by-side. These subtle color differences, though hard to distinguish for non-professionals, create significant differences in quality and price.

• Click to visit the GIA official website: What is diamond color?

Carat

Diamond weight is measured in carats, with 1 carat being equal to 200 milligrams, allowing carat weight to be accurate to two decimal places. As a unit of mass, one carat is further divided into 100 points, serving as a smaller unit of measurement—for example, a 20-point diamond = 0.2 carats. All other factors being equal, the larger the diamond, the higher its value. However, even if two diamonds have the same carat weight, their value (and price) can differ significantly because a diamond's value also depends on the other three standards of the 4Cs: clarity, color, and cut.