What makes a good diamond?

Regardless of the Four C’s, you want a diamond that reflects as much light as possible. Most people prefer the light reflecting properties of a diamond and the icy white-blue color of one that is of good quality and has few inclusions. The cut is at the root of the brilliance of a diamond. It is the most important characteristic in the Four C’s. No matter how highly rated the diamond may be graded in color, clarity, and carat, if the diamond is poorly cut, it will not refract and reflect any light, therefore greatly reducing the sparkle. So no matter the size or color of the diamond the best cuts are ideal. These should be rated as either Excellent, Ideal2, or Star129.

A good guide to a good diamond is to first look at the best cut possible, then clarity, then color, then carat. Also, diamonds with a clarity rating better than SI1 and color rating greater than I will ensure that the diamond is of good quality and brilliance. Before all others, there is a 5th unspoken C that determines if a diamond is of good quality. This C is Certification. While this does not have anything to do with the physical characteristics of the diamond, it is used to verify the grades of the diamond. These certificates are documentation of quality by a third party. This means that the diamond is not certified by a buyer or seller so it lowers the possibility of a diamond scam. Diamond certificates contain all the detailed information about the diamond and that quality in reference to the 4C’s. They also feature various security features to ensure that the diamond is original. It is important that the certificate is from a reputable diamond grader such as the following:

    • Gemological Institute of America (GIA)
    • American Gemological Society (AGS)
    • European Gemological Laboratory (EGL)
    • Diamond High Council (HRD)
    • International Gemological Institute (IGI)
    • International Confederation of Jewelry, Silverware, Diamonds, Pearls, and Stones (CIBJO)

Making sure that the certificate is from a certified grader ensures that the certificate and diamond are authentic and that all the information on the report is correct.

What are the 4 C's of diamonds?


The diamond color evaluation of most gem-quality diamonds is based on the absence of color rather than the presence of color. If a diamond is chemically pure and structurally perfect the diamond has no hue or color. There are a number of processes that can change the color of the diamond to enhance their appearance. These include: paintings and coatings, irradiation and heat, high-pressure high-temperature annealing, and low-pressure high-temperature annealing. While there is nothing wrong with treating diamonds to change their color, it is important to disclose any treatments or special case requirements. GIA’s (Gemological Institute of America) D-to-Z diamond color-grading system is the process used to measure the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to master stones of established color value. D is the best color grade and Z is the worst, which implies the diamond is cloudy or yellowish in color. These diamond colors are not considered fancy- color diamonds because they do not occur outside of the normal color range. Generally, the color of the diamond is not the most important factor, and it is recommended that one should look for the specific shape they want first and focus on cut quality. Cut quality will affect how brilliant the diamond looks once it is set in the ring.


Diamond clarity refers to the absence of inclusions and blemishes. It covers all things in a stone that affect the free passage of light. An inclusion is any material that is trapped inside of another mineral while that mineral forms. These can include crystals, liquid, gas bubbles, or even fractures. Inclusions reveal how a diamond is formed and can even determine whether it is a natural or synthetic gemstone. Generally the fewer inclusions there are in a stone the more valuable it is. There are treatments that can be used to try and minimize the impact of an inclusion, but some inclusions cannot be removed. The GIA’s grading scale, from best quality to lowest quality is as follows:

    • Flawless (FL)
    • Internally Flawless (IF)
    • Very, Very Slightly Included (VVS)
    • Very Slightly Included (VS)
    • Slightly Included (SI)
    • Included (I)

For the average buyer, knowing the intricacies of grading is not necessarily important. Rather, you should keep in mind that higher grades will be more brilliant and durable and lower grades will be more cloudy and less structurally sounds. Determining the clarity of a diamond should be done with a trained eye and is usually under 10x magnification. Size, number, and location of inclusions also affect the clarity of the thing. If the diamond is bigger or if the inclusion is bigger, it is easier to see. Tiny inclusions may be more difficult to see in smaller diamonds, but the larger the diamond, the larger the viewing surface area. The quantity of inclusions also matters. Even if they are tiny, if there are a lot of them it can cause the diamond to look unattractive. Lastly, the location of an inclusion can affect the visibility of it. The worst place to have an inclusion on a diamond is the table facet because it is the largest facet on the diamond (around 52-62% of the width).


Often the cut of a diamond is thought of shape, but a diamond’s cut grade is more about how well the diamond’s facets interact with light. The cut of a diamond is crucial to the stone’s final beauty. Of all the 4c’s it is the most complex and difficult to analyze. The GIA cut grading scale involves ratings beginning at (best to worst) excellent and continues to very good, good, fair, and poor. To determine the cut grade, the GIA calculates the proportions of facets that influence the diamond’s face-up appearance. This allows the diamond to be evaluated on how it interacts with light to create a desirable visual effect. Some desirable effects that a good quality diamond has are:

    • Brightness- internal and external white light reflected from a diamond
    • Fire- the scattering of white light into all the colors of the rainbow
    • Scintillation- the amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond.

While the number of facets on a diamond affects the overall brilliance the most, other characteristics to look out for are symmetry and polish.

Carat Weight:

Carat weight can be the most confusing C when it comes to buying a choosing a diamond. The carat is the unit used to measure the diamond’s weight. The bigger the carat, the larger the diamond, and usually more expensive. While it is a typical rule of thumb that larger diamonds are more expensive, it does not automatically make the diamond higher quality. Larger diamonds are typically rare so they tend to be more expensive in that aspect. But a large diamond with large or multiple inclusions may sell for less than a diamond that is half its weight that is blemish-free and crystal clear. A metric “carat” is defined as 200 milligrams. Each carat is subdivided into 100 ‘points.’ This method allows for precise measurements and a jeweler may describe the weight of a diamond below one carat by its points rather than the carats.

Gemstones: Synthetic vs. Natural:

There are many terms used to describe synthetic gemstones such as artificial, lab-grown, lab-made, and man-made, etc. All of these are used to identify gemstones that have been made in laboratories. The processes used to synthesize gemstones may mimic or reproduce natural processes and they may use the same ingredients. However, they are made in a lab. As the name implies, natural gemstones are stones that occur in the natural world without the influence of human activity. Some synthetic stones are made using chemicals that are similar to those that are found in nature and form the stones. Therefore these stones may be real gemstones, but not natural gemstones. Depending on the process used to make the stones some synthetic ones may even have inclusions that are found in naturally made stones. There are many distinctions between synthetic and natural gemstone, they can be difficult to identify. While it is difficult to tell the difference between a natural and synthetic gemstone without a microscope, usually, synthetic gemstones tend to be really rich in color and have virtually free of inclusions. Natural gemstones almost always have some type of inclusion or color differentiation. Such as diamonds, natural gemstones can be authenticated with a certificate of authenticity.

Most Common Types of Gemstones:

Gemstones are classified into categories: {precious and semi-precious stones. The difference between the two stones has no real scientific backing, but are classified based on how sought after they are. The most popular being a diamond. The gemstones that fall into the precious category are:

    • Diamonds
    • Rubies
    • Sapphires
    • Emeralds

These are the most sought after gemstones and usually are expensive and of high quality depending on the characteristics they possess. They are also more rare and high in value. Any other stone outside of the precious category is considered semi-precious and the list of semi-precious stones is quite extensive. With that being said, the most commonly found and sought after stones include:

    • Aquamarine
    • Lapis Lazuli
    • Quartz
    • Amethyst
    • Rutilated Quartz
    • Citrine
    • Pink quartz
    • Aventurine
    • Tiger’s Eye
    • Cornelian
    • Topaz
    • Tourmaline
    • Garnet
    • Opal
    • Turquoise
    • Agate

When these categories were formed it was mainly due to the rarity and value of the four precious stones, but today there are some semi-precious stones that are of more value than precious stones, but continue to be less sought after. They usually are worth more than less quality precious stones but tend to be rarely found in nature such as pearls. Pearls are an organic stone that originates from a biological process which makes it incredibly difficult to find. Organic stones can originate from animals or vegetables and are considered gemstones because they have characteristics, behaviors, and properties that credit them as such. Some popular organic gemstones include:

    • Pearl
    • Amber
    • Nacre

Factors That Make a Good Gemstone:

Two major characteristics that make gemstones good quality and value are their hardness and wearability. Hardness is described as the gemstone’s ability to resist scratching from outside elements. Hardness in gemstones only scientifically refers to that characteristic and nothing more. Hardness depends on the bonds that hold the atoms together within a crystal structure. The bonding is evident in the ease with which the layers separate. If the lower layer is harder than the top layer, then it will furrow, or scratch. Each mineral is ranked on the Mohs Scale of Hardness which is as follows (hardest to softest):

    • 10- diamond
    • 9- corundum
    • 8- topaz
    • 7- quartz
    • 6- feldspar
    • 5- apatite
    • 4- fluorite
    • 3- calcite
    • 2- gypsum
    • 1- talc

Quantity refers to a gemstone’s ability to resist blows. Most gemstones are considered brittle, but there are some that have “tough” tenacity such as: cryptocrystalline quartz, chalcedony, and jade. Both of these characteristics contribute to the gemstone’s wearability. If the stone is soft or brittle, the brilliance and longevity of the gemstone would decrease over time. Many people often bump their jewelry on objects in their everyday life or put hands inside of things like pockets and purses and soft gemstones would not be able to stand up to the elements. A grade higher than 7 on the Mohs scale is considered a gem that is hard enough for normal jewelry use. There are popular gems such as opals and pearls which are softer than a 7, but quickly deteriorate and are considered display gems. Wearability is graded much like other characteristics of gems and rank from excellent to display only with excellent being very wearable, possibly every day, and Display Only being only for collection purposes. The full scale is as follows:

    • Excellent
    • Very god
    • Good
    • Poor
    • Display only

As for diamonds, the Four C’s play a large part in the quality of a gemstone and the contribution to the value very similarly. The main difference between gemstones and diamonds is that the color for gemstones is more important than the cut as opposed to diamonds. Jewelers would rather a gemstone with a lower quality cut if that means the facets do not wash out the color or muddies the color. Cutters prefer rough that is transparent and without many inclusions. Some gems are rarely eye-clean, so some inclusions are acceptable in those materials. Color is always the highest priority in gemstones as it is 60% of the gem’s overall value and cut being 10%. The rest of a gemstone’s value is comprised of size at 10%, shape at 5%, and locations at 15%. For many colored gems, the country of origin greatly affects the value. If the stone is comprised of certain older, historical sources it is more valuable rather than one that is comprised of newer less known sources.