Diamonds

Science Summaries

This simplified evaluation chart of diamond quality, summarizes "The 4 Cs" of diamond quality grading, which determine value.



The chart summarizes the evaluation factors of Carat, Cut, Color, and Clarity, and lists the other factors that determine a diamond's value.

1. Carat

The carat is a unit of weight.
One metric carat consists of 100 "points".
One metric carat = 1/5 gram, or 200 milligrams

As the size of a diamond goes up, the price goes up exponentially.
Prices can range from $2,000 up to $60,000 per carat.

2. Cut

Type of Cut
1. Round - Also called Brilliant, the most preferred cut
2. Princess - Square cut, second most preferred

Other Cuts:
Baguette cut (trapezoid)
Emerald cut (octagon step cut)
Heart cut
Marquise cut (pointed oval)
Oval cut
Pear-shaped cut
Rectangle cut
Square (step cut)
Trillion cut

3. Color

$$$$$ - $$$$ - $$$ - $$ - $ ----->

G.I.A. Scale:
D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z

D, E, F - Colorless (most valued)
G, H, I, J - Nearly colorless
K, L, M - Faint yellow
N, O, P, Q, R - Very light yellow
S, T, U, V - Light yellow

4. Clarity

$$$$$ - $$$$ - $$$ - $$ - $ ----->

GIA Scale:
F, IF, VVS1, VVS2, VS1, VS2, S1, S2, S3, I1, I2, I3

F (flawless) is best, followed by
Internally Flawless, followed by
Very, Very Small Inclusions (2 grades) followed by
Very Small Inclusions (2 grades) then
Small Inclusions (3 grades), then
Imperfect (3 grades)

In addition to "The 4 C's" of diamonds, other important factors that determine a diamond's value are:

Culet (the very small face on the bottom)
E- Excellent, VG- Very Good, G- Good, F- Fair, P- Poor

Depth Percentage

Finish - E- Excellent, VG- Very Good, G- Good, F- Fair, - Poor

Fluorescence

Measurements

Polish - E- Excellent, VG- Very Good, G- Good, F- Fair, P- Poor

Proportion

Symmetry - E- Excellent, VG- Very Good, G- Good, F- Fair, P- Poor

Table percentage


Measurements:
Crown Angle - 25-43°
Crown Height
Culet Size
Diameter
Girdle Thinkness - 50-95%
Pavilion Angle - 39-44°
Pavilion Depth
Star Length - 40-70%
Table Depth
Table Size - 50-70%

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