The 4C’s of Diamond Grading and Additional Valuation Factors
The 4C’s of diamond grading establish the foundation for determining a diamond’s value. However, there are additional factors that also influence its valuation.
The 4C’s:
Carat Weight
The most obvious factor in determining a diamond’s value is its weight, measured in carats (1 carat = 0.2 grams). Diamonds are valued on a per-carat basis, with price increments at certain weight thresholds. For example, a 1.00-carat diamond can be worth up to 50% more than a 0.99-carat diamond of the same quality, despite the minimal size difference. Additionally, two diamonds of the same weight can appear different in size if one has more depth, affecting their value based on other quality factors.
Cut
Cut quality, or the ‘make’ of a diamond, refers to its proportions and finish, impacting its internal reflection and dispersion of light. This factor can affect a diamond’s value by up to 50%. The cut determines the diamond’s brilliance and sparkle, making it essential to see a diamond before purchasing. Many diamonds are cut to maximize weight retention rather than beauty, which can lead to variations in value despite similar carat weights.
Colour
Diamonds are classified as ‘Cape Series’ or ‘Fancy Colored’. Most gem-quality diamonds fall into the ‘Cape Series,’ with colors ranging from colorless ‘D’ to light yellow ‘Z’. Colorless diamonds are more valuable, except for certain natural fancy colors like pink, purple, red, and blue. The color of a diamond is assessed under laboratory conditions using a master set of diamonds and graded on the International Color Grading Scale.
Clarity
Clarity is determined by the number, size, relief, and positioning of inclusions or imperfections within the diamond. These imperfections are graded on the International Clarity Grading Scale by trained gemologists. Each clarity grade represents a range of quality, making it important to visually examine diamonds rather than relying solely on grades, as diamonds with the same clarity grade can vary in desirability.
Additional Valuation Factors:
Shape
Round brilliant cut diamonds are typically more valuable than other shapes due to higher rough diamond weight loss during polishing and their popularity. Other shapes may vary in value based on current trends.
Transparency
Transparency affects a diamond’s ability to conduct light and is influenced by factors such as inclusions, cloudiness, and graining. A diamond with high clarity can still be less valuable if it lacks transparency.
Fluorescence
Fluorescence causes diamonds to glow under ultraviolet light. While it usually does not affect appearance, in some cases it can cause a diamond to appear ‘milky’ or ‘cloudy,’ impacting its value.
At The Gold Company, we use these criteria, alongside assessments by the Diamond Certification Laboratory of Australia (DCLA), to determine the value of your diamonds, ensuring a fair and comprehensive evaluation.
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