How Do Gemological Labs Grade Diamonds?

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Diamond remains to be the most frequently bought fine gemstone on planet earth, so simply learning how to evaluate them for their worth is a very essential skill in today's society. This is especially true for collectors, but also applies to everyone who's ever planned to buy an engagement ring, wedding band, or even anniversary jewelry pieces.



Jewelry seems to be the go-to gift for many people, due to the fact that value is held within its beauty. It's a lasting type of gift, rather than a fading one, like flowers or chocolate. This aside from the pure visual appeal of diamonds sparkling against shimmering bands of metal and gold.

When diamonds are priced, the number one criteria people seem to consider (aside from weight, obviously), is color. Near-colorless to colorless diamonds sell more per carat than rubies, sapphires and emeralds do per year. The colored stone market is approximately 10 to 15% of the diamond market for jewelry in most thriving countries.

Color is something that governs value in gemstones, either by intensity or absence. For most diamonds, the absence of color is the way they rank higher up in the value chain.

Many decades ago, the Gemological Institute of America created what we now call the normal D-Z grading scale for diamonds. This can be explained fairly simply, but can take years of practice to understand by "eye" or comprehend visually.

Now the scale starts at the highest grade; "D" which means that a stone is totally devoid of color. There won't be any yellow, brown, gray or even fancy hues present visually in the stone. The grades of "D, E and F", are actually considered to be in a category called "colorless". The scale goes down further to the next category of grades labeled "G, H, I and J" or near-colorless. "K, L and M" are faint yellow or faint brown, and the further down the alphabet a graded stone goes, the more color it will possess.



It's important to note that each letter actually represents a very narrow range of color. So you can have two E colored diamonds with slightly different saturations of yellow for example. Though despite this, it would be extremely difficult to visually differentiate two stones that have the same grade from each other (in terms of color alone). This range per grade is tight, and can be easily misinterpreted by inexperienced diamond buyers.

At a grade of "Z", a stone will exhibit prominent color. This is usually in a yellowish hue, but can also be in other hues as well. Stones with colors more saturated than a "Z" would be labeled with the term "fancy colored diamond", and can have adjective-phrase grades like fancy vivid greenish blue or fancy light pink. Usually fancy colored diamonds with hues other than yellow, gray, black and brown will actually command higher prices than near-colorless (and often colorless) diamonds. Fancy colored red diamonds are among the rarest of all gemstones, and some are reported to cost over a million dollars per carat.



Color is definitely one of the biggest factors for diamond evaluation. Here in the Philippines, a majority of upscale socialites tend to select color grades of G-H and above.

Our laboratory is currently developing a curriculum for gemstone identification and diamond grading knowledge, which tentatively will start at the later parts of this year. If you'd like to learn more on grading color, as well as continue on to the other quality grading factors- clarity, cut and carat weight, then feel free to join our updater's list for when details get released regarding our workshops.

Gemcamp laboratories also makes use of color-grading "masterstones" which represent the 'end-values' of each color grade's narrow range. For example, a masterstone of the color grade designation "G" represents a G-graded stone with the most possible color in its range. Any stone with more color compared to the G-master, will be considered as an H colored stone.

While a standard system exists, not all laboratories will give the same color and clarity grades to a specific stone. Variations are present within the strictness and conformity of each independent laboratory, and even among those institutions with similar styles of grading.

Our doors are always open for sessions of diamond grading and evaluation, feel free to schedule an appointment with one of our GIA graduate gemologists via our Facebook page.

Gemcamp Laboratories

A Discovery Institute for Gemstones and Gemology

Our resident gemologists believe in encouraging public trust within the jewellery industry through shared education, value transparency and professionalism.

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