STORIES - Why Cut Quality Matters So Much

A diamond sparkles, but why does one diamond shine so much more than another, even if they’re the same size and color? The answer lies in one of the most crucial factors: cut quality.

What Is Cut Quality?

Cut quality refers to how well a diamond has been cut, not its shape (like round or oval), but the precision of that shape’s execution.

It determines how light moves within the diamond and how much brilliance and fire the stone reflects. Even a flawless diamond with perfect color won’t look its best without a high-quality cut.

The Official GIA Cut Grades

The Gemological Institute of America (GIA) assesses cut quality using a five-tier scale, this applies specifically to round brilliant cuts, which follow the strictest standards:

  • Excellent
    Maximum brilliance, perfect proportions and craftsmanship

  • Very Good
    Beautiful sparkle, with minor variations in proportion or finish

  • Good
    Decent brilliance, but some light escapes from the stone

  • Fair
    Noticeable loss of sparkle due to poor light return

  • Poor
    Little to no brilliance, dull appearance

How Does Light Work in a Diamond?

A diamond acts like a hall of mirrors for light.
When perfectly cut, light enters from the top, reflects from facet to facet, and returns to the eye, creating the signature sparkle everyone desires.

But if a diamond is cut too deep or too shallow, light escapes from the sides or bottom, meaning lost brilliance you’ll never get back.

Fun Facts About Cut Quality

  • The ideal brilliant cut was first calculated in 1919 by Marcel Tolkowsky, based on math, optics, and beauty.

  • Cut quality includes proportions, symmetry, and polish, it's a form of craftsmanship, not just mechanical precision.

Why byJACKY Chooses Excellence

At byJACKY, we select only diamonds with Excellent to Very Good cut grades, to ensure every stone shines the way it’s meant to: vibrant, luminous, and full of character.

Looking for that perfect diamond for your ring or custom piece?
Book an appointment and let’s create your dream jewel, together.

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