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IIG: International Institute Of Gemology | Beyond 4C’s (Fluorescence)

FLUORESCENCE IS GOOD OR BAD?

When shopping for an engagement diamond ring, first of all we look for the 4Cs: clarity, cut, color, and carat. But did you know there are other elements to consider when choosing a diamond? Fluorescence is a very important factor as well. It may feel misleading, but it might surprise you to find out that fluorescence can make a diamond look one or two shades better in color or sometimes even oily and dull too, Let us understand this parameter which can make more than 10% price difference in diamond value.

WHAT IS FLUORESCENCE?

Diamond fluorescence refers to the intensity of a colored glow (usually blue) that is visible when a diamond is exposed to UV light. In some instances, diamonds with strong fluorescence may look milky and lifeless in daylight, but in most cases, the appearance of a diamond with strong fluorescence is rarely affected. Diamonds with none or a faint fluorescence are rarer than those with a strong or very strong fluorescence.

For diamonds with faint or no fluorescence, this does not affect the natural appearance of the diamond but a more fluorescent diamond glows in natural sunlight too and this can be perceived as being undesirable in a white diamond.

The degree of fluorescence can vary as around one-third of all diamonds show some fluorescence, with 95% exuding a blue color – though green and yellow fluorescence diamonds can also be found, though much rarer than those with a blue hue.

Approximately 25% to 35% of them exhibited some degree of diamond fluorescence when examined with a standard long-wave UV lamp.

Diamond glow under UV light – Fluorescence

GRADING FLUORESCENCE

According to the intensity of fluorescence diamonds are graded as None, Faint, Medium, Strong, and Very Strong for fluorescence. Diamonds can fluoresce in a variety of colors. These include orangy yellow, yellow, orange, red, white, and green. However, Blue is the most common color of diamond fluorescence. If the fluorescence is Medium, Strong, or Very Strong, the color of the fluorescence will be noted on the grading report.

  • Faint
  • Medium
  • Strong
  • Very strong
  • Extremely strong

None, Nil, Negligible – No fluorescence, no influence on color.
Faint, Slight – Weak fluorescence, not a significant influence on color (barely perceptible).
Medium – Average fluorescence, small influence.
Strong, Extremely Strong – Strong fluorescence, substantial color influence.

HOW IMPORTANT IS DIAMOND FLUORESCENCE?

In a small number of diamonds, the presence of fluorescence creates a hazy, milky, oily, or cloudy appearance. For this reason, very strong fluorescent diamonds can be valued lower than similar diamonds with fluorescent ratings of Faint or None.

How Fluorescence Affects Price:

V. STRONG STRONG MEDIUM FAINT
D-F IF – VVS2
VS1 – VS2
SI1 – I3
-10 to -15%
-6 to -10%
0 to -3%
-7 to -10%
-3 to -5%
0 to -1%
-3 to -7%
-1 to -2%
0%
-1%
0%
0%
G-H IF – VVS2
VS1 – VS2
SI1 – I3
-7 to -10%
-3 to -5%
0%
-5 to -7%
-2 to -3%
0%
-1 to -3%
0 to -2%
0%
-1%
0%
0%
I-M IF – I3 0 to +2% 0 to +2% 0 to +2% 0%

For a precise summary of the effects of fluorescence on price, use the chart below. The effect on price varies depending on the degree of fluorescence, diamond color, and clarity. For example, according to the chart, an E color diamond of VS1 clarity and Strong Fluorescence will tend to sell for 3-5% less than a like diamond with no fluorescence. Alternatively, a J color diamond of any clarity and Medium fluorescence will typically sell for up to 2% more than a like diamond with no fluorescence. While clarity has no bearing on the appearance of color and fluorescence, it does impact price. This is because customers who gravitate towards higher clarity tend to be more adverse to the presence of fluorescence.

Fluorescence can enhance or detract from the beauty of a diamond. The bluish tint can improve a lower-color diamond (J-M color rated) by canceling out the faint yellow, resulting in a colorless appearance.

However, in a very high-color diamond (D-F color rated), fluorescence may have the opposite effect.

CONCLUSION: SHOULD ONE BUY A FLUORESCENT DIAMOND?

The final decision on whether or not to buy a fluorescent diamond is obviously customers, just remember that the four C’s (color, cut, clarity, and carat) is far more important than fluorescence, but also parameter “Fluorescent” is important to buy the right diamonds as the right price. Fluorescence doesn’t negatively affect the appearance of the diamond unless and until it is in the highest degree as Strong or Very Strong fluorescence.

IIG India

International Institute of Gemology is an educational institute imparting knowledge about Gems and Jewellery. IIG has educated over 1,00,000 professionals excelling in the Gems and Jewellery industry. An institute par excellence offers education programs with certifications that hold global credibility. Having a stronghold in the industry for five decades, IIG has accelerated the quality of education in the Gems and Jewellery sector. IIG works towards bringing the best practices of the Gems and Jewellery industry under one roof.

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