How do we appraise the value of a diamond?


Our jewelry store Orlando is sometimes visited by people with beautiful jewelry that they want to convert into cash or simply get an appraisal for. Most people in our area know that we are experts at appraising fine jewelry like diamond rings, gold necklaces, pendants with emeralds, rubies, diamonds, or other precious stones and that we will give them a precise appraisal that they can use as a reference to selling their heirloom trophies.

We thought it would be good information to communicate how we evaluate the monetary value of a diamond.

Examining the Diamond – The Four Cs

When you bring us a diamond, we evaluate it on the basis of the 4 objective criteria called the “Four Cs”: Cut, Color, Clarity, and Carat weight. These criteria are the standard metrics of the evaluation set by the Gemological Institute of America (GIA).

What are they?

1. The Cut:

The cut of a diamond refers to how well it’s been cut from its raw form. It’s not about the shape but about the quality of the artistry. We examine six factors: symmetry, polish, depth and table percentages, crown and pavilion angles, and girdle thickness.

Symmetry: Symmetry is the arrangement of the diamond’s facets and how proportional they are to one another. If a diamond has good symmetry, the aspects will align adequately and reflect light more evenly, giving the diamond a more brilliant appearance. Misalignment of elements can lead to poor light reflection, diminishing the diamond’s sparkle.

Polish: Polish is the smoothness of the diamond’s facets. When a diamond is cut and shaped, the polishing wheel may create microscopic surface defects. These might include polish lines and burn marks. If a diamond has excellent polish, it means no minute polish lines are visible under 10x magnification. Poor polish can dull the diamond’s shine as it affects how light interacts with the surface.

Depth Percentage: Depth percentage is the ratio of the diamond’s depth (from the culet, or point, to the table) to the diamond’s width. This affects how light travels within the diamond. If the depth percentage is too high, the diamond may appear darker as light leaks out the sides. If it’s too low, the diamond may appear washed out as light leaks through the bottom.

Table Percentage: This is the ratio of the table (the flat facet on the top of the diamond) compared to the width of the diamond. A well-proportioned table percentage ensures optimal light reflection. A table that is too large or too small can negatively impact the diamond’s brilliance.

Crown and Pavilion Angles: The crown is the top portion of the diamond above the girdle, and the pavilion is the bottom part below the girdle. The angles of the crown and pavilion play a crucial role in how light reflects within the diamond. Too steep or shallow grades could leak light out instead of reflecting the viewer’s eye, reducing the diamond’s sparkle.

Girdle Thickness: The girdle is the widest part of the diamond, forming a band around the stone’s perimeter. It can vary in thickness, and its condition can range from Extremely Thin to Extremely Thick. If the girdle is too thin, the diamond is prone to chipping. If it’s too thick, it can affect the diamond’s proportions and overall beauty.

We use a scale from Excellent to Poor defined by GIA to evaluate each of these six factors:

Excellent: In this highest grade, the diamond’s proportions, facet alignment, and polish deliver the highest fire and brilliance. The diamond has been cut to allow almost all incoming light to be reflected out of the crown, maximizing its sparkle.

Very Good: Diamonds in this grade still have significant fire and brilliance. Although they may allow a small amount of light to escape through the pavilion (bottom), the difference in sparkle compared to Excellent cut diamonds is often difficult to perceive without professional training.

Sound: Good-cut diamonds offer good brilliance and fire, although light leakage through the pavilion may be noticeable. This grade may be a reasonable choice for those seeking to balance cut quality and price.

Fair: A fair-cut diamond allows a noticeable amount of light to escape from the pavilion. While it may still be attractive to some buyers, others may find its level of sparkle disappointing.

Poor: The poorest grade on the GIA scale, a flawed cut diamond has been cut to proportions that allow a significant amount of light to escape through the pavilion. These diamonds typically have a dull appearance with slight brilliance or fire.

Our evaluation starts with the cut of your diamond. We grade it according to the GIA system.

Second step in the process, we evaluate the color of your diamond.

2. The Color:

The color is evaluated on a scale: D at the top (colorless diamond) to Z at the bottom (the diamond has a light yellow or brown hue). I’ll compare your diamond to master stones under controlled lighting conditions to establish the grade.

Here is a brief breakdown:

D, E, F – Colorless: The diamond shows virtually no color. These are the highest color grades, and such diamonds are scarce.

G, H, I, J – Near Colorless: While still having a minimal color, when these diamonds are graded face down (the standard way to grade color), detecting any color is challenging. However, when mounted, they can appear colorless to most people.

K, L, M – Faint: These grades show a slight hint of color, a faint yellow when viewed face down. The color may not be as noticeable when mounted, especially in gold settings.

N, O, P, Q, R – Very Light: When viewed face down, the diamonds have an easily noticeable light yellow (or brown) hue. This color may be seen even when mounted.

S through Z – Light: When viewed face down, the diamond has a clear yellow hue or a light brown hue, and the color is noticeable even when mounted.

This color grading system is used primarily for white diamonds. Color diamonds ― those with solid and distinct colors like blue, pink, or yellow ― have a different grading system based on the intensity of their color.

3. The Clarity:

This word indicates an absence of inclusions. It also denotes an absence of blemishes. The top clarity grade is “Flawless” (zero inclusions and zero defects are visible when the diamond is examined under a 10x magnifying device). The lowest Clarity grade is “Included”. This is when you can see with the naked eye that the diamond has inclusions or features blemishes.

Inclusions and blemishes refer to the stone’s internal and external characteristics. They are often formed during the diamond’s creation process deep within the Earth and can also result from the diamond cutting process.

Inclusions: These are characteristics found within the diamond. Examples of inclusions are:

Crystals or Mineral Inclusions: Other minerals trapped within the diamond while it was forming. The nature of these inclusions, whether colorless or colored, can affect the overall appearance of the diamond.

Clouds: These are a group of tiny crystals that are too small to be seen individually and create a hazy region inside the diamond.

Feathers: These are fractures within the diamond that usually occurs naturally due to immense pressure under the Earth’s surface. They can sometimes reach the surface of the diamond.

Needles: These are long, thin crystal inclusions that can give a diamond a distinctive appearance.

Pinpoints are tiny crystal inclusions that can only be seen under magnification.

Blemishes are external characteristics that affect the surface of the diamond. Examples of blemishes are:

Polish Lines are fine; parallel lines are left on the diamond’s surface by polishing.

Grain Boundaries: If the diamond’s growth process is interrupted, this can result in irregular crystal growth, leading to grain boundaries visible on the surface of the diamond.

Nicks are minor damage to the diamond’s girdle, usually caused by wear and tear.

Scratches: These are usually lines on the surface of the diamond, often caused during the cutting and polishing process.

Natural: Part of the original rough diamond’s surface, or skin, is left on the polished diamond, usually on the girdle.

When a diamond features inclusions and shows blemishes, its clarity is graded lower, and its value goes down.

While a flawless diamond (no inclusions or blemishes visible under 10x magnification) is extremely rare and valuable, the naked eye can’t see many inclusions and blemishes. Diamonds graded as “slightly included” (SI1, SI2) or even “included” (I1, I2, I3) can still be beautiful to the untrained observer.

4. The Carat Weight

This is a simple weight measurement, but size can also significantly impact value. The larger a diamond is, the rarer. The rarer, the most desirable.

But what is a “carat”?

Carat is defined as a unit of weight for diamonds and other gemstones: 1 carat = 200 milligrams, or 0.2 grams.

“carat” comes from the “carob” seeds historically used to balance scales in Oriental bazaars. These seeds are extremely uniform in weight and were thus a standard reference. The modern “metric carat” was adopted in 1907 at the Fourth General Conference on Weights and Measures, and has since been used worldwide.

How does the value of carat vary on the international market?

The value of a stone increases exponentially with its carat weight. This is because larger diamonds are rarer than smaller ones. So, a diamond weighing a single carat is more valuable than two diamonds of the same quality but weighing ½ each.

However, the value also depends on the three other factors mentioned earlier among the Four Cs.

A smaller diamond could be worth more than a larger one if the smaller diamond has better clarity, color, and cut.

On the international market, the value of a carat varies with supply and demand. For example, if there’s a large demand for one-carat diamonds and a shortage in store, the price per carat will be higher than if supply was abundant. Factors such as global economic conditions, consumer demand, and even mining activities can impact diamond prices.

Furthermore, specific sizes are more valuable than others:  ½ carat (0.50), ¾ carat (0.75), and 1 carat (1.00) — tend to have significantly higher prices per carat because of increased demand. When a diamond’s weight crosses these magic sizes, the price per carat can jump considerably.

Diamonds are priced on a per-carat basis. For example, if a 1-carat diamond is priced at $5000 per carat, the total cost of the diamond would be $5000. If a 2-carat diamond is priced at $8000 per carat, the total cost of the diamond would be $16,000 so not only does the value per carat increase as the size of the diamond increases but the total price increases even more significantly.

These are the Four Cs. Every expert gemologist uses them to grade a diamond, and most experts arrive at the same conclusion regarding price range because every expert is trained to a high level of proficiency.

However, because of the variations in supply and demand, the value of your diamond will vary on the international market depending on what is currently in oversupply or short supply. If your appraisal does not meet your expectations and the explanation does not convince you, I suggest you get a second appraisal.

If this new appraisal doesn’t meet your expectations, I suspect the market has too much supply, which depresses prices. You may want to wait a little while before selling your diamond: the market will always rebound.

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