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When it comes to determining the value of a diamond, our mind immediately goes to the 4 main attributes that make up the stones appearance (and rarity). Of course we mean the 4Cs; Color, Clarity, Cut, and Carat size.

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This is 100% accurate, but what if we told you there is much more than meets the eye when trying to measure a diamond’s true value? There actually 29 nuances, and we will be taking a look at each and every one in this 3 part series.

You can find part 2 here, and part 3 here.

In this Part 1 we will be looking at 10 factors (other than the 4Cs) that ultimately affect diamond price. Let’s begin!

1. The Angle of the Crown

For those a little rusty on terminology, the crown is the very top part of the diamond, and its proportions play a significant role in how the diamond can absorb and refract light. Ideally, the crown should have the same angle measurements on either side for perfect symmetry.

The larger the difference, the greater the impact on the gem’s cut and brilliance. Now in order to avoid any misconception, the angle has to do with the “slant” of the crown.

2. The Depth Percentage of the Crown

Only referring to the proportions of the crown, its depth is what determines how the light will travel within the diamond. Note that the crown’s depth percentage in relation to the depth of the pavilion and thickness of the girdle are what tell you where most of your diamond's weight will be concentrated.

3. The Size of the Culet

Opposite of the Crown, the culet is the point located on the bottom of the diamond. Note that this point applies to diamonds that have been shaped with a “brilliant cut”.

Culets are usually slightly faceted (flat) and are what causes the light to scatter in many directions. Larger culets however will detract from this ability and might even appear like a black spot at the bottom of the diamond.

So, the smaller the culet, the better the light will be reflected, and the higher the diamond’s value will go.

4. The Angle of the Culet

Again talking about brilliant cuts here; ideally the culet should be placed at the very center of the diamond’s bottom side, measuring 98.5 degrees. Any deviation from this and the gem's symmetry will be off, thus causing diamond price discounts.

5. An Off-Centered Culet

Similar to the point above, the culet of a diamond needs to be at the dead center of the stone. Any derivation, even at the slightest, will lead to the culet not being a perfect triangle, thus reducing the gem’s light performance.

6. Table Width Percentage

The upper flat facet, also known as the table of the diamond, should ideally be between 53-57%. A table that is too large will detract from the “sparkle” caused by the crown’s facets, making the light escape only from the top center.

On the other hand, a table that is too small will cause an uneven light refraction. In both cases, the stone’s overall value will be negatively affected.

7. An Off-Centered Table

Since the table is where most of the light enters and exists the diamond, it needs to be perfectly centered in order to have perfect symmetry and light performance. This is especially true in brilliant cut gems, a perfectly symmetrical diamond will show off a beautiful pattern leading up to a perfect point (the culet), a beauty and craftsmanship worthy of a price increase.

8. Depth Percentage

Ratios are everything when cutting a diamond. If the diamond’s depth (top to bottom) is significantly larger or smaller than its diameter, it will become dark in appearance because it will no longer return an optimal amount of light.

This is usually hard to determine when the diamond is set so extra attention is needed.

9. The Depth Percentage of the Pavilion

The Pavilion is the portion of the stone located directly under the girdle and is directly related to the diameter of the stone. Ideally the depth should be between 42.2%-43.8%.

As we said in the depth percentage section above, a pavilion which is disproportionate will negatively affect light refraction.  Again, the pavilion thickness in relation to the depth of the crown and the girdle are what help us determine where most of our diamond’s mass is located.

10. The Thickness of the Girdle

The girdle is what attaches the crown to the pavilion and ideally it should be equally thick on both sides. Usually girdles are ranked as thin, medium, and slightly thick.

While this might not play a significant role in light refraction, the thickness will take away from a diamond’s beauty.

This concluded Part 1 of our series. Stay tuned for Part 2 coming shortly. Until then if you have any questions, please feel free to let us know! And as always feel free to follow us on Twitter and like us on Facebook.

For more interesting diamond and investment facts check out the links below:


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