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First, identify the diamond shape desired by the recipient. If you do not know and cannot find out, consider round or princess cut. Set a carat weight minimum based on the recipient’s preferences. If they have their heart set on a one carat diamond, even the most beautiful half carat stone will be a disappointment. First, identify the diamond shape desired by the recipient. If you do not know and cannot find out, consider round or princess cut. First, identify the diamond shape desired by the recipient. If you do not know and cannot find out, consider round or princess cut.
fiwl_diamond_guide_1006_191 CUTWhen we speak of cut we are more interested in the proportions of the diamond as opposed to its shape (Round Brilliant, Marquise, Pear, Princess, etc.) Every diamond regardless of its shape gets it brilliancy and scintillation by cutting and polishing the diamond facets to allow the maximum amount of light that enters through its top to be reflected and dispersed back through its top. In a correctly cut, “well made” stone the light that enters is dispersed properly back through the diamond’s top facets. When a stone is cut too shallow or too deep the light that enters through the top is allowed to escape through the diamond’s bottom and does not allow the maximum beauty of the diamond to be realized.


Diamonds come naturally in every color of the rainbow. However most people are concerned with diamonds in the white range. The Gemological Institute of America (GIA) rates the body color in white diamonds from D (colorless) to Z (light yellow). The best color for a diamond is no color at all. A totally colorless diamond allows light to pass through it easily, resulting in the light being dispersed as the color of the rainbow. Colors are graded totally colorless to light yellow. The differences from one grade to the other are very subtle and it takes a trained eye and years of experience to color grade a diamond.


The clarity of a diamond is determined by the amount and location of flaws, or blemishes, in the diamond when viewed under 10 power (10x) magnification. GIA rates clarity grades in diamonds from Flawless to Imperfect 3. Most diamonds contain very tiny birthmarks known as “inclusions.” An inclusion can interfere with the light passing through the diamond. The fewer the inclusions, the more beautiful the diamond will be. Diamonds have the capability of producing more brilliance than any other gemstone. A diamond that is free of inclusions and surface blemishes is very rareā€¦and therefore very valuable.


This is the weight of a diamond measured in carats. As the carat weight of a diamond increases so does its rarity and therefore its price. One carat is divided into 100 “points,” so that a diamond of 75 points weights .75 carats. The carat-weight of a diamond is the easiest measurement to determine. Most importantly, two diamonds can be of equal carat-weight, but their value can differ greatly due to their cut, color, and clarity.

fiwl_diamond_guide_1007_191 Most people who receive diamonds as a gift or for an engagement have a shape preference. While other factors (such as price and quality) should be determined by the purchaser, the choice of shape should include input from the receiver of the diamond, if at all possible. This is especially true for fancy shape engagement diamonds.Unless a particular preference has been expressed, consider a round diamond. Round diamonds tend to have more brilliance and scintillation than other shapes, they accommodate almost any ring setting, and never go out of fashion.

Length to width ratio has a major impact on the shape of a fancy diamond. Every Lumera Diamond is shown in its correct length to width ratio so that you can easily see the difference between diamonds of the same shape (e.g. a narrow vs. a fat marquise, or a square vs. a rectangular princess cut). If you are not sure about your preferences, search for a shape you like, and then view diamonds of various length to width ratios within that shape until you find what you like. Then, focus your search on diamonds that are within roughly 10% of your ideal length to width ratio (e.g. if you decide that your ideal radiant cut diamond has a 1.50 L/W ratio, focus your search on radiants between 1.35 and 1.65).

fiwl_diamond_guide_1008_191 Look for diamonds that fall just under popular carat weights such as 1/2 ct. 3/4 ct., 1 ct., etc. Because these diamonds fall just shy of the popular weight, they are often sold at a slight discount compared to diamonds of full weight. For example, a .90 carat diamond will typically cost less on a price-per-carat basis than a full 1.00 carat diamond. Visually, they are difficult to distinguish. In fact, a smaller carat weight diamond may have a diameter equal to that of a heavier diamond, making it appear the same size when viewed from above.The most popular carat weights for engagement diamonds are between one and two carats. If a diamond under .75 carats is a budget necessity, consider a marquise cut, which appears larger than other shapes of equal carat weight, due to its elongated cut.
fiwl_diamond_guide_1009_191 Unlike the other “Cs” (Carat Weight, Color, and Clarity), the various Cut grades in existence today were not originated by GIA. Even though retailers use common terms to describe Cut (such as Excellent, Very Good, Fair, Poor) the terms are not uniformly defined or applied. In fact, a diamond seller may assign any cut grade they choose, based on any set of factors they wish. One retailer will use terms such as “Signature Ideal”, “Ideal”, and “Excellent”; while another uses “Ideal” to describe all three, and another uses “Excellent” for all. Be cautious when comparing cut grades from different retailers, as they are most likely inconsistent.Also, be aware of diamond sellers who assign their own cut grades in place of what GIA has already assigned to a particular diamond. Many popular websites and retail stores display their own, more generous Cut rating in place of the GIA grade.

To avoid confusion or misrepresentation of any diamond, Lumera uses the same cut grades as employed by GIA, and does not engage in “cut inflation” by creating other grades (“signature”, “super ideal”, etc.).

Cut grade is the most important factor in determining the overall appearance of a diamond because a poorly cut diamond will seem dull even with excellent clarity and color. Conversely, a well cut diamond can have a slightly lower color (G-H) or clarity (SI1-SI2) and still look quite beautiful, due to its superior ability to create sparkle and brilliance.

For superior brilliance, choose a diamond with a Cut grade of Very Good or Excellent for round diamonds, and Good or better in fancy shape diamonds. When choosing a diamond in this range, make sure its symmetry and polish are Very Good or Excellent, so that the impact of the above average Cut is not obscured.


Any culet size of Medium or smaller will be invisible to the naked eye, and have no negative impact on a diamond’s appearance.


An Extremely Thin girdle is more susceptible to chipping, and for that reason should be avoided for diamonds that are to be set in a ring. Earrings or pendants are less exposed to rough contact and so are less susceptible to chipping around the girdle. Avoid even Very Thin girdles in Princess Cut diamonds, as this shape already has sharp corners more prone to chipping. If you do purchase a Princess Cut diamond with a Very Thin girdle, consider setting it in a style that covers and protects the corners.


For diamonds with a polish grade of Excellent to Good, any polishing defects are not visible to the naked eye, and should have no impact on the diamond’s overall appearance.

For diamonds with clarity grades of I1 or lower, even a polish grade of Fair is acceptable, since these diamonds already possess internal inclusions that are visible to the naked eye, making any polish markings less relevant.

For diamonds less than .75 carats, any polish grade of Fair or better will not affect the appearance of the diamond to an untrained observer.

Poor is the only polish grade that should be avoided regardless of the size or clarity of the diamond. For this reason, Lumera does not carry diamonds with a polish grade of Poor.


For diamonds with a symmetry grade of Excellent to Good, symmetry should not be used as a primary factor in choosing a diamond, since each of these grades is possible in diamonds of exceptional appearance.

Symmetry is more important in diamonds of VVS2 Clarity and higher, since the very subtle defects produced by Fair or Poor symmetry (which can resemble pinpoint inclusions), would compromise the diamond’s otherwise flawless appearance.

Despite its modest impact on appearance, symmetry has a significant impact on price; a diamond with Excellent Symmetry and Polish may be priced 10%-15% higher than a diamond with Good Symmetry and Polish. This premium has more to do with consumer’s perceived value of “excellent” grades, than the actual affect on a diamond’s appearance.

Because diamonds with Poor symmetry have defects visible to the naked eye, these diamonds should be avoided in all cases.

fiwl_diamond_guide_1010_191 The vast majority of untrained observers (and many gemologists) cannot distinguish a color grade from the one just above or below unless the diamonds are compared side by side in a controlled environment. Even when side-by-side, changes in color are difficult to detect in I color and higher diamonds.Color becomes much harder to detect once a diamond is set in a ring and placed in an environment that contains color (as opposed to the all white background used in color grading). For instance, an H color diamond may look as colorless as a D when set in a ring under normal lighting conditions, especially if the two are not compared side by side.

For the best value in what would appear to the naked eye as a colorless diamond, look for G-J diamonds. Because color is easier to detect in larger diamonds (just as a large carafe of white wine shows more color than a small glass), opt for G-H in diamonds over 1 carat, and I-J for those under 1 carat. Once set in a ring, these diamonds will look just like higher color grade diamonds. Instead of investing in higher color, invest in higher cut, the most important factor in a diamond’s brilliance.

Because diamonds with more facets reflect more light, they tend to hide color better than other shapes. So, consider round, princess or other modified brilliant cuts over step cuts such as emerald or asscher if you are concerned about color.

If you are concerned primarily about carat weight, and are on a tight budget, consider a yellow gold setting and a brilliant cut diamond in the K-L color range. The yellow gold will complement the faint body color of the diamond.

If, while shopping for a diamond, you are ever given a color range (e.g. G-H) as opposed to a specific grade, the diamond is not certified by GIA. The seller is only estimating the diamond’s color using GIA terminology.


Colorless (D-F) fluorescent diamonds sell at a 5-15% discount to non-fluorescent diamonds since the fluorescence is perceived as a defect. In fact, the visible effects of faint to medium fluorescence are perceptible only to a gemologist using a special UV light source.

Because the fluorescent glow is usually blue (which is the complementary color to yellow) fluorescence can make diamonds of I-M color appear up to one grade whiter. For this reason, I-M diamonds tend to sell at a slight premium when they possess Medium to Very Strong fluorescence.

Overall, fluorescence should not be a major factor in the diamond purchase since its effects on appearance are negligible, if not slightly positive. The exception would be to exercise caution in purchasing a diamond with strong or very strong fluorescence in D-H color diamonds (which do not possess enough yellow color to offset the blue fluorescence).

fiwl_diamond_guide_1011_191 If you cannot tolerate imperfections, even those you cannot see, choose a VVS2 or better diamond. About 10% of all diamonds sold fall into this category.The most popular range is the VS1-VS2 diamond. These diamonds appear flawless to the naked eye, and are a fraction of the price of a truly flawless diamond. Almost half of all diamonds purchased fall into this range.

The next most popular range is SI1, where the inclusions are usually not significant enough to impact the appearance of the diamond for the casual observer. Often, customers will opt for this clarity range in exchange for a higher cut or color grade. This combination often results in a beautiful, lively diamond with imperfections detectable only upon close inspection. In diamonds under 1 carat, the same can be said for an SI2 grade. In diamonds over 1 carat (where clarity is more important, and SI2 inclusions are often easier to detect), an SI2 is often half the price of a VS1 diamond. About one third of diamonds sold fall into the SI1-SI2 range.

If you are primarily concerned with size and price, I1 may be your best clarity option. While the inclusions are visible to the unaided eye, many customers find it to be well worth the sacrifice for what it affords in size.

The larger the diamond, the easier imperfections are to detect; therefore Clarity becomes more important. For diamonds over 2 carats, a clarity grade of VS2 or higher is the safest bet for avoiding any signs of visible inclusions. In diamonds between 1 and 2 carats, clarity grades of SI1 or better will not have inclusions easily visible to the naked eye. In diamonds under 1 carat, clarity should be considered the least important of the traditional 4 Cs.

Brilliant-cut diamonds (such as round, princess, cushion, oval, pear, and marquise) hide inclusions better than step cuts (emerald, asscher). When purchasing a step-cut, move up one clarity grade (e.g. purchase a VS2 instead of an SI1 if you desire the lowest grade that has no visible inclusions).

If, while shopping for a diamond, you are ever given a clarity range (e.g. SI1-SI2) as opposed to a specific grade, the diamond is not certified by GIA. The seller is only estimating the diamond’s clarity using GIA terminology.

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