Anatomy of a Diamond: A Guide for Discerning Jewelry Buyers

Diamonds are not only a symbol of luxury and elegance but also a significant investment. Understanding the anatomy of a diamond can help you make an informed purchase, ensuring you get the best quality for your money. This guide will delve into the key components of a diamond's structure, specifically focusing on round brilliant cut diamonds, the most popular shape. Save these tips to ensure you're choosing a well-proportioned diamond that maximizes brilliance and sparkle.

Key Components of a Diamond's Anatomy

1. Star Length
   • Star length refers to the distance from the center of the diamond's table (top flat surface) to the star facets' tips. It affects the diamond's scintillation, or the sparkles seen as the diamond moves.
2. Table Size
   • The table is the largest facet on a diamond. The table size percentage is crucial; an ideal range for round brilliant diamonds is typically between 54-57%. A proper table size helps balance the diamond's brilliance and fire.
3. Girdle Thickness
   • The girdle is the thin band around the widest part of the diamond. Girdle thickness is graded from extremely thin to extremely thick. A medium to slightly thick girdle is often preferred, providing durability without compromising the diamond's appearance.
4. Crown Angle and Crown Height
   • The crown is the upper portion of the diamond above the girdle. The crown angle and height influence how light is dispersed within the diamond, contributing to its fire. Ideal crown angles range from 32 to 36 degrees.
5. Total Depth
   • Total depth is the height of the diamond from the table to the culet (the bottom point). It's expressed as a percentage of the diamond's diameter. For round brilliant cuts, a depth percentage of 59-62% is typically ideal, balancing light performance and diamond size.
6. Lower Girdle Facet Length (Half Facets)
   • These facets are located below the girdle and can affect the diamond's sparkle and scintillation. A length of 75-80% is generally preferred for round brilliant cuts, providing an attractive balance of brilliance and fire.
7. Culet
   • The culet is the small, flat facet at the diamond's bottom. A small or non-existent culet (graded "none" to "small") is ideal, as a large culet can appear as a dark spot when viewed from the top.
8. Pavilion Depth and Pavilion Angle
   • The pavilion is the lower portion of the diamond, below the girdle. The pavilion depth and angle are critical for light reflection. An ideal pavilion angle for round brilliant diamonds is typically 40.6-41.2 degrees.

Tips for Choosing a Well-Proportioned Round Brilliant Cut Diamond

1. Prioritize Proportions Over Carat Weight: A diamond with excellent proportions will look more brilliant and fiery than a larger diamond with poor proportions.
2. Check the GIA or AGS Report: Trusted grading reports provide detailed information about a diamond's cut, including table size, crown angle, and more. Use this data to assess the diamond's quality.
3. Avoid Extremely Thin or Thick Girdles: While a thick girdle adds durability, an extremely thick one can make the diamond look smaller than its actual weight. Similarly, avoid extremely thin girdles to prevent chipping.
4. Focus on Ideal or Excellent Cut Grades: These grades ensure the diamond has optimal proportions for maximum brilliance.
5. Consider the Overall Appearance: While technical specifications are essential, also trust your eye. A well-cut diamond should dazzle with its light performance.