Like you, diamonds are unique. 34 different factors affect the price of a diamond.Speak With a Specialist
Diamonds naturally come in every color of the rainbow but the most common are those with a slight yellowness. The more common diamond colors are ranked on a scale from D (absolutely colorless) to Z (naturally yellow).
The rarest and most expensive diamonds are either D-colorless or of a natural fancy intense color such as blue, yellow, pink, or the most rare-red. However, not all colored diamonds are natural; some are treated with harmless radiation to artificially enhance color. These diamonds are significantly less valuable than natural colored diamonds because they are not as rare. A diamond’s color should be determined when it is “loose” or not in a piece of jewelry yet. This is because the color of the jewelry can play visual tricks on the human eye making a diamond appear more yellow in yellow gold or whiter in platinum.
The most complex factor affecting a diamond’s price is the cut of a diamond. Diamond cutting is still done by human hands. When a diamond cutter cuts a stone, they must make difficult decisions about how large it will be, what shape it will become, and how many imperfections will be left in the final product. After these decisions are made, it is the craftsmanship and fine motor skills of the diamond cutter that determine how much the stone will sparkle and how much attention it will draw. The slightest mistake can ruin a diamond’s symmetry and, in doing so, dramatically decline the beauty and price of the stone. Even a flawless and colorless stone can become dull when badly cut.
When properly cut, a diamond will reflect almost all of the light that enters it through its top. If improperly cut, some to most of the light will exit out of the bottom or side of the stone. A properly cut diamond will have symmetrical facets (the windows and mirrors of the stone), good proportions (not too deep or too shallow), and careful finishing details (like flawless polishing and permanent treatments). If properly cut, the diamond will return a white shaft of light from its top (called brilliance), sparkle every time that it moves (called scintillation), and send rainbows out of its many facets (called fire or dispersion).
These three elements of a diamond’s light mix in unique and fascinating ways and it is solely a matter of preference from person to person as to what the best mixture is. Another matter of preference is the shape that a diamond is cut into. Any shape other than a classic round is called a "fancy cut." Some of the more common fancy cut shapes are:
Fancy cut diamonds make a very strong statement and are a beautiful and unique way to uniquely represent your personality.
Clarity refers to the number of “inclusions” that are found inside a diamond. Inclusions are scratches, trace minerals, or other tiny characteristics that can detract from the way that light bounces from mirror to mirror (known as facets) within a diamond.
It is extremely rare to find a diamond without inclusions; when one is found it is ranked “flawless” and is very costly. Inclusions are distinguishing characteristics which represent the uniqueness of each diamond and are often called the diamond's fingerprint because no two stones are exactly alike.
The number of inclusions in a diamond is ranked on a scale based on the visibility and location of these little characteristics when the diamond is under 10x magnification. Two common diamond grading houses are the Gemological Institute of America [GIA] and the American Gem Society [AGS]. Each has its own unique way to rank and ‘grade’ a diamond’s clarity. Below is a chart showing the rankings from Flawless to ‘Included’ and which AGS numbers correspond with which GIA letters so you will be better able to compare “apples to apples” in your diamond search.
"Feathers" look like a bird’s feather in the stone and can be a structural problem if any of the tiny cracks are close to the diamond’s surface.
"Pinpoints" look like clear or white bubbles within the diamond and can change the way light is distributed depending on their size.
"Carbon Spots are black, brown, or other colored dark dots or specks in the diamond. Many low priced I clarity stones are priced low because of distracting carbon spots in obvious places that cannot be hidden.
"Clouds" are actually just a group of pin point inclusions. Clouds look like empty masses within the diamond and can cause the diamond to be more susceptible to breaking if close enough to the surface.
"Needles" look like empty thin tubes and can be very obvious or small. If they are close to the surface or stretch long enough they may cause the diamond to be more susceptible to cracking.
When jewelers refer to a diamond’s carat they are actually referring to the weight of the stone, not the size. In jewelry, the size of gemstones are measured in millimeters and, since diamonds can be cut shallow, deep or ideally it is impossible to accurately convert a diamond’s carat weight into an exact mm size. However, a very rough conversion can be made. Despite the ability to very roughly convert carat weight to size, the only accurate way to know the true carat weight of your diamond is to weigh it. Thus, 1 carat has become universally known as being a metric weight of 0.02 grams. The weight of a diamond has the most significant impact on its price. Since the larger a stone is, the rarer it is, one 2 carat diamond will be more expensive than the total cost of two 1 carat diamonds of the same quality. The carat of a diamond is often very important to people when shopping but it is a mistake to sacrifice too much quality for sheer size.
The ‘crown' of a diamond is the top part of the stone. The crown's proportions affect the “cut” and light return of a stone. Both sides of the crown should have an equal angle measurement (determined based on the “slant” of the crown versus the straight “top” line of the crown). A misangled crown tells you that your diamond lacks symmetry. A misangled crown adversely affects the cut and brilliance of a diamond.
The “culet” is the bottom point of a diamond and it is usually slightly flat (faceted). The culet will react like any other facet, reflecting light in many directions. A larger culet will detract from the light performance of the diamond. It is one of the potential causes for the appearance of a black hole in the bottom of a diamond.
The ideal culet should be positioned in the exact center of the bottom of the diamond and should measure 98.5 degrees. Any deviation from this will adversely affect the symmetry of a diamond and will therefore detract from its brilliance.
Table Width Percentage
If the diamond's table (upper flat facet) is too large then light will not play off of any of the crown's angles or facets and will not create the sparkly rainbow colors that are so beautiful in diamonds because it will all simply escape from the top center. If it is too small then the light will get trapped and that attention grabbing shaft of light will never come out but will “leak” from other places in the diamond. The ideal table percentage is 53-57%.
Depth percentage of a diamond is the ratio of the total depth of the diamond (from table to culet or top to bottom) as compared with the total diameter (or width from side to side). If a diamond's depth percentage is too large or small the diamond will become dark in appearance because it will no longer return an attractive amount of light.
Crown Depth Percentage
Crown depth percentage varies from the overall depth percentage because it only refers to the crown's (top section of the diamond) proportions. Just as with the crown angle, the depth of the crown determines the way light will operate in the diamond. The crown depth percentage in relation to the pavilion depth percentage and the girdle thickness indicate where much of your diamond's weight will be concentrated.
Pavilion Depth Percentage
Pavillion depth percentage of a diamond is the depth of the pavilion (portion of the diamond below the girdle) as it relates to the diameter of the diamond. The ideal pavilion depth is 42.2%-43.8%. A shallow or deep pavilion will adversely affect light performance. The pavilion depth percentage in relation to the crown depth percentage and the girdle thickness tell you where much of where the diamond's weight will be concentrated.
The girdle is the part of the diamond that attaches the crown to the pavilion. A perfect girdle will be equally thick when comparing one side to the other and will be ranked as thin, medium or sometimes slightly thick. A thick girdle adds weight where you cannot see it and raises the weight of the stone making it more expensive but for less visible size or beauty.
Non-Parallel Table and Girdle
The table and girdle of a diamond not being cut on parallel planes undermines the symmetry of the diamond. Symmetry is critical to light performance. A non-parallel table and girdle will affect, but usually will not be shown, in the crown angle measurements of the stone.
Off Center Culet
Determined by drawing an imaginary line through the exact middle of a diamond. If the culet is askew and not dead center, the culet will not be a perfect triangle. An off center culet undermines the symmetry of a diamond. Symmetry is critical in maximizing light performance.
Off Center Table
The table of the diamond is where white light or “brilliance” enters and exits the stone. A perfectly centered table is very important to maximize the symmetry and therefore the light performance of the diamond. Looking down into a diamond with an off center table, you will often see the side of the diamond instead of endless light and the perfect point that is the culet.
Misshapen facets are usually an indication of other problems within the cut of the diamond. Each facet of a diamond is designed in a certain shape and should maintain this shape all around. The facets are set in these shapes because they act as windows and mirrors that allow light in and out of a diamond. When they are the wrong shape the light is funneled and reflected incorrectly.
A diamond cutter will sometimes add an extra facet to a diamond to mask or remove an imperfection or natural. Though the extra facet removes an external blemish, it also undermines the diamond's symmetry and light performance.
Table is Not a Regular Octagon
The table of a diamond should be a perfect octagon. A misshaped table leads to other misshapen facets and undermines the diamond's light performance.
Out of Round Girdle Outline
The girdle outline of a diamond should be perfectly round (or whatever shape it has been cut to be). A diamond cutter will sometimes cut a diamond out of round to preserve weight or to remove a blemish or natural. An out of round girdle outline undermines the symmetry and therefore light performance of a diamond.
Crown and Pavilion Misalignment
When the facets of the crown and the pavilion on either side of the girdle do not point to one another. This causes the diamond to appear to be twisted slightly. If the crown and pavilion are misaligned the diamond will handle light incorrectly. This twist can be from mild to severe.
Facets Not Properly Pointed
The facets of a diamond must create an exact point at each intersection to properly catch light and maximize scintillation. A flattened facet side can be a polishing or initial cutting mistake and will result in reduced sparkle of the diamond. To create a perfectly faceted diamond is an arduous and time-consuming task.
The result of the diamond cutter's failure to properly angle the facets that meet the girdle. A wavy girdle will adversely affect the look and light performance of a diamond.
Naturals on Crown, Girdle, and Pavilion
A natural is a portion of the diamond's original rough surface that hasn't been polished. Naturals are sometimes left along a diamond's girdle if leaving it allows the cutter to produce a heavier carat weight stone. However, extra weight from naturals does not add to the visible size or beauty of the diamond but does add to the price.
Refers to the level of detail accomplished by the diamond cutter in the final phase of fashioning a diamond from the rough crystal. The polish level is ranked on a scale based on the visibility of little imperfections on the outside surface of the diamond when it is under 10x magnification.
Described as naturally compressed lines in the internal structure of the diamond. Internal graining will cause a diamond to appear dull.
White light is commonly referred to as brilliance. It is produced by light coming in through the various top facets and bouncing off of the bottom facets. Brilliance is what gets your diamond noticed from across a room and can only be quantitatively measured by a GemEx Brilliance-Scope. Though limited quantitatively, the human eye is able to qualitatively measure the brilliance of a diamond.
The term used for the radiance or sparkle of the changing color light rays that appear when the diamond is moved or when the light source changes. Scintillation can only be quantitatively measured by a GemEx Brilliance-Scope. Remarkably, the human eye is able to qualitatively measure the scintillation of a diamond.
The ‘dispersion' or colored light of a diamond is commonly referred to as ‘fire.’ Fire is the rainbow that should jump from a diamond. Fire can only be quantitatively measured by a GemEx Brillance-Scope Analyzer that determines what percent of the total diamond returns bright colored light to the observer. Though unable to measure quantitatively, the human eye is able to qualitatively measure the fire of a diamond.
Fluorescense is the level to which diamonds will glow under ultraviolet light. All natural diamonds fluoresce to varying degrees, though standard testing equipment will detect fluoresence only when it is more evident. The presence of phosphorous in the internal structure of a diamond is what causes fluorescence. Though fluorescence can cause some diamonds to appear ‘murky' under normal sunlight, fluoresnce can actually enhance a diamond's whiteness and brilliance. Fluoresence should not automatically be considered a detriment to the beauty of a diamond.
Fracure filling is when a chemical compound is injected into a fracture in a diamond (usually those that reach the surface of the diamond). Since this process artificially enhances the clarity of a diamond, it renders the diamond less valuable than one whose clarity is not artificially enhanced. This process makes it nearly impossible to accurately grade the diamond. Fracture filling also compromises the strength of a diamond because the filling does not always stand-up to everyday goldsmith procedures and practices; possibly resulting in the complete cracking of the stone.
High Pressure & High Temperature [HPHT “Color Enhancement”]
HPHT is the process where a diamond is subjected to extremely high pressure and temperature to artificially enhance the color of a diamond by changing the microscopic carbon spots within it from gray, brown or black into another color. The color that will be produced cannot be controlled but is permanent after treatment. Since HPHT is an artificial process these diamonds are not as valuable as naturally colorless or fancy colored diamonds.
Process where laser beams are used to bore into carbon inclusions naturally embedded in diamonds. The drilling removes the inclusion with acid but also jeopardizes the natural beauty of the diamond by leaving little white drill lines.
Lab-grown diamonds, also referred to as created diamonds, man-made diamonds, synthetic diamonds, or engineered diamonds are artificially produced in a laboratory over a few weeks. Their chemical properties, pure carbon crystal stucture, brilliance, and hardness are almost identical to those of a natural diamond. Unlike natural diamonds, formed in the Earth's crust billions of years ago, lab-grown diamonds are not considered rare because they can be produced in limitless quantities an a matter of weeks. Anyone who sells lab-grown diamonds must clearly disclose to the consumer that they are not natural diamonds.
Social, Ethical and Environmental Responsibility
It is not entirely ironic that diamonds, the world's most valuable product, are mined in some of the most poverty stricken areas on Earth. There are a variety of reasons that this type of advantage is taken by unethical mining companies and governments. However, there are certain diamond mining companies and diamond cutters that adhere to a high level of social, ethical and environmental responsibility. These companies are committed to investing profits into improving the quality of life in these regions. They invest in health care, education, wildlife protection, and land regeneration. The diamonds sold by these companies may be priced at a slight premium. To learn more about how Day's Jewelers pledges to source ethically and responsibly mined diamonds, visit our Conflict-Free Diamonds education page.
*All information and pictures on this page are for educational purposes only and are not the sole property of Day’s Jewelers, rather this page is an accumulation of images and information from many resources.