Diamonds can be graded by color. While using a letter scale has become popular in modern times, diamonds were graded in the past using more romantic terms such as ‘first water’ (perfectly transparent and free from flaws) and ‘water white’ (a very clear preferred white diamond color).
Wesselton Diamonds
Another term used to color grade diamonds is Wesselton. Wesselton was the actual name of a diamond mine that produced gorgeous white diamonds. Today the tag 'Wesselton' is used for color grading diamonds. Wesselton refers to diamonds that are H white; Top Wesselton refers to colors F and G (sometimes F is referred to as Top Wesselton+).
Gemological Institute of America (GIA) Color Grading Scale
How to interpret the letter scale: D indicates the highest color quality in the colorless group; F indicates the lowest in that same group.
- D, E, F – Colorless
- G, H, I – Near Colorless
- K, L, M – Faint Color
- N through R – Very light yellow
- S through Z – Light yellow
GIA Clarity Grading Scale
Combine the color grading scale with the clarity grading scale to evaluate the value between diamonds.
- FL – Flawless
- IF – Internally flawless
- VVS1 and VVS2 – Very, very slight inclusions
- VS1 and VS2 – Very slight inclusions
- S1 and S2 – Slight inclusions
- I1, I2 and I3 – Imperfect
Costing Out a Diamond
To give some sort of reference point for the cost of a diamond, at the publish date of this article, a VS1, G .33 carat diamond retails for $600. A .33 carat diamond that is S1, G costs $450 and an I1, G in the same size is $300. While the difference in price between the three is nominal in the .33 carat size, it increases in a non-proportionate fashion in diamonds approaching 1 carat and larger.
Fluorescence
Many diamonds fluoresce under ultraviolet rays. This means the gemstone will throw off a color when it’s under direct sunlight or fluorescent light fixtures. A example of these fixtures are the banks of long tubed lights found in offices and stores. Blue, yellow and white are the three most commonly thrown off colors with blue being the most common of the three.
Fluorescence rarely affects the selling price of a diamond unless the diamond appears murky in color. A murky looking diamond is a by-product of blue and yellow being thrown off together under both daytime and fluorescent lights.
Certification
If purchasing a diamond, unless a GIA type certificate is offered listing the grade, the purchaser relies on the seller’s veracity and knowledge of diamonds.
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