Grading Diamonds and Colored Gemstones Information by Northwest Jewelry

Grading Diamonds

Have you heard about the Four C’s of diamond grading? Most people have some familiarity with them: Color, Clarity, Cut, and Carat weight. When buying either loose diamonds or a diamond already set, a consumer is often given information about their diamonds grade, either in the form of an appraisal, or a certificate of authenticity. This information will generally include the diamond’s color and clarity characteristics, as well as the carat weight. Sometimes the diamond’s proportions are included as well. It is important to have a generally accepted grading system so as to have an objective way to determine a diamond’s value.

Color:
Most diamonds fall in the range of colorless to yellowish-brown. The generally accepted color range grades are D-Z. All other factors being equal, colorless diamonds have more value than those with faint or light color. This does not apply to fancy-colored diamonds, which are graded differently.

Following are the grades with brief descriptions of their colors:

DEF: colorless
G-J : near colorless ~ most of the commercially available diamonds fall within this range
K-M: faint
N-R: very light
S-Z : light

Clarity:
There are eleven generally accepted clarity grades. Clarity measures the “imperfections” in a gemstone and rank them based upon their size and position on the gemstone. Flawless and internally flawless gemstones will have a higher value, if all other factors are equal, while I-1, I-2 and I-3 gemstones will have lesser value.

Clarity grades:
Flawless
Internally Flawless
VVS1 and VVS2: very, very slightly included
VS1 and VS2: very slightly included
SI1 and SI2: slightly included
I-1, I-2 and I-3: included

VS, SI, and I gemstones have eye-visible inclusions. The inclusions in VVS gemstones are visible under magnification.

Cut:
The cut of the diamond also affects the value. How well a diamond gemstone is cut will determine how much light is reflected, which will affect the diamond’s brilliance.

Carat Weight:
Generally speaking, the larger the gemstone, the higher the value. At each carat level, the price increases significantly. If you are in the market for a one-carat gemstone, price the stones slightly less than a carat to get a price break.
Grading diamonds is not an exact science, but by using the standards generally accepted, the consumer can expect to have a good idea of a diamond’s value.

Grading Colored Gemstones

How can you tell what quality a colored gemstone is? How are colored gemstones graded?
Like diamonds, there is a generally accepted system in grading colored gemstones. Although they are graded in terms of clarity and color like diamonds, that is where the similarity in grading systems ends. And generally, the consumer is not presented with grading information at the time of purchase.

Color is generally the most important factor in determining a gemstone’s value. Each type of gem has a range of color that is preferred. Gemstones that fall within this range have a higher value than those outside of it.

Clarity, a way of judging how free a gemstone is of internal and external imperfections (known as inclusions), is also considered when grading a gemstone. Clarity not only affects the appearance of a gemstone, it can affect its durability, depending on its size and location.

Cut is also an important factor. When comparing two gemstones, if the color, clarity, and size are similar, the one with the better cut will be worth more. The amount of “brilliance” a gemstone has reflects how good the cut is.
Even without formal training, most people can do a fairly good job of judging the color and cut of a colored gemstone. Does it catch your eye? Is it relatively free of inclusions (assuming it is a gemstone where inclusions are not expected)? How much brilliance does it have? Beauty is in the eye of the beholder to some extent, when considering cut and color.

Judging clarity, however, is different depending on the type of gemstone you are considering. There are three clarity types in colored gemstones:
Type 1- These gemstones are expected to be “eye-clean”. In other words, without magnification and upon a close inspection with the naked eye, it is difficult to see any flaws in the stone. Aquamarine and blue topaz are two Type I gemstones.
Type II – Minor eye-visible inclusions that do not detract from the gemstone’s appearance are expected in Type II gems and do not decrease the value, depending on the size and location. Sapphires and garnets are examples of Type II gemstones.
Type III – We expect these gemstones to have very visible inclusions and this does not necessarily detract from their value, taking into consideration the size and location of the inclusions, as well as the color and cut. Emerald and watermelon tourmaline are examples of Type III gemstones.

Following are some of the most common colored gemstones and their types: