CGA Diamond Grading & Gemological Science Flashcards

Which of the four Cs is considered the most important factor in determining a diamond's value?

Answer: Cut

Cut is considered the most important of the four Cs because it directly determines how well a diamond reflects and refracts light, affecting its overall brilliance and beauty.

On the GIA diamond color scale, which grade represents a colorless diamond?

Answer: D

The GIA color scale begins at D (colorless) and runs through Z (light yellow or brown), with D being the highest and rarest color grade.

A diamond with a 'VS2' clarity grade contains inclusions that are:

Answer: Very slightly difficult to see under 10x magnification

VS2 (Very Slightly Included 2) diamonds have inclusions that are minor and somewhat difficult to see under 10x magnification but are typically invisible to the naked eye.

What is a diamond's 'fluorescence' and how does it typically affect value?

Answer: Glow under UV light; strong fluorescence often decreases value in colorless diamonds

Diamond fluorescence is the visible light emitted when exposed to UV radiation, and strong blue fluorescence in colorless to near-colorless diamonds can make them appear hazy, typically reducing their market value.

Which diamond cutting style maximizes fire and brilliance through triangular and kite-shaped facets?

Answer: Brilliant cut

The brilliant cut, with its 58 triangular and kite-shaped facets arranged to maximize light return, produces the greatest fire and brilliance of any cutting style.

What does the term 'table percentage' refer to in diamond grading?

Answer: The ratio of the table facet's width to the diamond's overall diameter

Table percentage is the ratio of the table facet's width to the diamond's average girdle diameter, expressed as a percentage, and is a key factor in evaluating cut quality.