No two diamonds are exactly alike, but diamonds do fall into distinct categories. Learn more about diamond grades and cuts in this guide.
Did you know the Koh-i-Noor diamond ranks as the most expensive diamond in the world with no known price? This 105.6ct, oval-shaped diamond was reportedly mined in India in the 1300s.
The Koh-i-Noor may exceed your budget, but you must know the classic 4Cs of diamond grades.
What are Diamond Grades?
The universal standard for judging diamonds emerged in the mid-twentieth century. GIA developed this standard grading system now known as the 4Cs. GIA remains the largest and most respected nonprofit source for gemological knowledge worldwide.
Color quality of diamonds rests in the absence of color. A pure, structurally perfect diamond will have no hue, like a pure drop of water.
GIA designated a color-grading system comparing the colorlessness of a stone to a masterstone. The masterstone has a defined color value.
The comparison stone is viewed under controlled lighting in optimal viewing conditions. The stone then receives a grade of D to Z.
The GIA system assigns the D grade to the stone considered colorless. As the color increases, the grade rises toward Z.
Natural diamonds occur when carbon undergoes a period of tremendous pressure and heat. This can cause internal marks called inclusions. Marks on the outside of diamonds are called blemishes.
Determining the clarity of a diamond involves evaluating the size, number, relief, nature, and position of these inclusions and blemishes. No diamonds are completely free of these flaws. Yet, the closer the diamond comes to purity and perfections the higher its value.
The GIA Clarity Scale includes 6 categories. Some of these categories are further divided for a total of 11 specific grades.
The ability to reflect light and intensely sparkle are hallmarks of diamonds. The cut does not refer to the shape of the diamond, but how well the diamond facets interact with light.
Expertise in precision, artistry, and workmanship creates a stone whose proportions, symmetry, and polish stunningly reflects light. Of the 4Cs, this is the most complex and technically difficult to assess.
The GIA Cut Grading System for a standard round brilliant diamond considers seven factors. The first three evaluate the general face-up appearance:
- Brightness looks at the internal and external white light reflected from the diamond
- Fire describes the scattering of the white light into all the colors of the rainbow
- Scintillation describes the diamond’s sparkle, including the patterns of light and dark in the reflections
The remaining four include:
- Weight ratio
These last four standards look at the diamond’s design and craftsmanship.
A diamond carat describes the unit of measure for a diamond’s weight. One carat equals 200 milligrams. To increase the precision of the measurement, carats are further divided into 100 “points”. If a diamond weighs less than 1 carat, its weight will be reported in points.
Shapes of Diamonds
Shape may not play a role in the GIA grading system. However, shape does influence shoppers’ desire for different diamonds. Explore these shapes and cuts:
- Round Brilliant
- Princess Cut
- Cushion Cut
- Emerald Cut
- Assher Cut
- Pear Shape
- Marquise Shape
- Heart Shape
- My Girl Diamond
An age-old favorite, the oval diamond rings, continue to be popular among more traditional shoppers.
Take your time. Diamonds are forever.
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