4 Cs

  • Carat weight

  • Color

  • Clarity

  • Cut

Carat Weight

The weight of a diamond is the Carat: 1 carat is equal to 0.20 grams. One carat can be divided into 100 points. A 0.75 carat diamond is equal to a diamond of 75 points and is equal to a diamond 3/4 carat. The industry uses various sorts of balances to measure the weight of a diamond. The carat is a measure that also applies for the other precious stones and gemstones. The carat of precious stones has nothing to do with the karats of golden alloys. A diamond which would weigh 0.9990 announces 1.00 carat and 0.9989 announces 0.99 carat.

Photo by OsvaldoGago

Photo by Roger Culos

Carob Tree(Ceratonia Siliqua)

The word carat is often mistaken with size, yet the carat is actually measured in weight. Nonetheless, the diamond's diameter also increases proportionally with the carat weight. The word carat derives from the Greek word “keration” meaning fruit of the carob. The Carob tree is an evergreen tree, with an edible pod containing seeds, which is native to the Mediterranean region. Carob seeds, surprisingly have quite a uniform weight of 0,20 grams, and therefore old civilizations used these seeds as a reference weight for precious gemstones. 

Color

A chemically pure and structurally perfect diamond is fully transparent with no hue. However, almost natural diamonds are not perfect. The color of a diamond may be affected by chemical impurities and structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. Diamonds are valued by closely they approach colorlessness. For example, the diamonds are discounted in price when the more yellow hue is detected, while intense yellow, pink, blue, red and  etc can be dramatically more valuable. The red diamonds of all colored diamonds are the rarest.

The majority of mined diamonds fall between white and yellowish or brownish; which is known as the normal color range. Diamonds of more intense color(usually yellow but in some cases red, green, or blue are termed fancy color diamonds.

Diamond Color Grading

Clarity

Natural diamonds are the result of carbon exposed to extremely high temperatures and pressure deep in the earth as the upper mantle. This process can result in a variety of internal characteristics called 'inclusions' and external characteristics called 'blemishes'. When a diamond is graded according to its clarity, a gemologist will inspect the diamond for inclusions and blemishes.

 

All grades reflect the appearance to an experienced grader when viewed from above at 10x magni-fication. Evaluating diamond clarity involves determining the size, number, position, nature and color(or relief) of these characteristics, as well as how these affect the overall appearance of the stone. 

Diamond Clarity Grading

Inclusions

  • Bearded girdle (BG)

  • Bruise (Br)

  • Cavities (Cv)

  • Chip (Ch)

  • Clouds (Cld)

  • Feathers (Ftr)

  • Grain center (GrCnt)

  • Included crystals or minerals (Xtl)

  • Indented Natural (IndN)

  • Internal graining (IntGr)

  • Knot (K)

  • Laser drill hole (LDH)

  • Needle (Nd)

  • Pinpoint (Pp)

  • Twinning Wisp (W)

Blemish

  • Abrasion (Abr)

  • Extra Facet (EF)

  • Lizard Skin

  • Natural (N)

  • Nick (Nk)

  • Pit (Pit)

  • Polish Line (PL)

  • Polish Mark (PM)

  • Rough Girdle (RG)

  • Scratch (S)

  • Surface Graining (SGr)

Cut

The cut is the only way to add value to diamonds as a gemstone with human technology. Of course,  the development of technology and the production cost have been lowered, so recently, diamonds can be synthesized

to make them... 

The way you cut the diamond determines its dazzling glow. Often diamond cut is confused with 'shape'.

The diamond cut grade is evaluated based on 'cut proportion, surface finish, and facet symmetry'.

Diamond Anatomy: A round brilliant diamond has between 57 and 58 facets

In general, diamond cut grade is evaluated by three factors. These three factors are as follows.

  • Proportion

  • Finish - Polish

  • Finish - Symmetry

Proportion

Proportion on loose diamond

Tolkowsky Ideal Cut Diamond Proportions

GIA Ideal Cut Diamond Proportions

What does Ideal Cut mean?

Due to its perfect proportions, an ideal cut diamond reflects nearly all the light that enters it through the table and crown of the stone.

Shallow

Ideal

Deep

Finish - Polish

  • The presence of more or less polish lines.

  • The presence of burn mark

  • If the stripes are too numerous, they are mentioned in remarks of the certificate.

Finish - Symmetry

  • The good alignment of the facets

  • The symmetry of the facets.

  • The centering of the culet and the table

Extra facets

Misalignment

Table off-center

Misshapen facet

Not parallel

Not properly pointed

Out-of-roung

Wavy girdle

Culet off-center

Illustration of  Ceratonia Siliqua

Burn Mark

How to Estimate a Diamond's Value

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