Diamond Fluorescence - Can it Really Affect Gemstone Color?

    When shopping for a gemstone, diamond fluorescence is a common factor that is often overlooked. It could be that many consumers aren't properly informed of this occurrence. However, it should not be an element that's to be ignored. Let's take a look at this phenomenon and how it can affect your stone.

    What Is Fluorescence?

    Fluorescence, also known as photo luminescence, is a characteristic of some diamonds which causes them to glow when exposed to ultraviolet light. This occurs when the boron atoms contained within a stone are stimulated by any source of UV lighting, such as natural daylight and black lights. The amount of glow that a stone emits will depend on the amount of boron atoms it has, and while the majority of stones fluoresce blue, other colors are possible. This can range from yellow, green, white, pink and red, like the Hope Diamond. The abbreviations for describing strength of fluorescence are as follows:

• N, NO, NON - No fluorescence
• F, FB, FT, FA - Faint or faint blue fluorescence
• SL, SLB, SLT - Slight fluorescence
• M, MO, ME, MD - Medium or moderate fluorescence
• S, ST, STB, STG - Strong fluorescence
• E, EX, EXB, EF - Extreme fluorescence

    Is This Good Or Bad?

    This phenomenon has caused many debates within the diamond industry, and in many cases, influenced the pricing of gemstones. The theory has been that diamond fluorescence has a positive impact on faint yellow stones, such as those graded K, L and M. For example, if a yellow stone fluoresces blue, it counteracts with the yellow, making it appear whiter. For this reason, these lower-colored gemstones that glow blue are higher in price than those that don't glow. On the other hand, the other theory proposed is that fluorescence can have a negative impact on colorless diamonds, such as those graded D, E and F. When viewed under ultraviolet light, a colorless stone that has a medium to strong glow will look oily or cloudy. This detracts from the beauty of the diamond, and as a result, brings down it's price by 10 to 30 percent.

    You Be The Judge

    In 1997, the Gemological Institute Of America (GIA) conducted a study on the effect of ultraviolet fluorescence on a diamond's appearance. A group of similar graded stones with various amounts of fluorescence were observed and commented on by participants. These participants included trained diamond graders, trade professionals (jewelers) and average observers (general public). The study concluded that for the average observer, fluorescence made no discernible difference. As for the experienced observers (graders and trade professionals), they did not agree on the affects of fluorescence. And contrary to the previous theories, the trained/experienced observers most consistently determined that stones which emit a strong glow were the ones with the best color.

    The bottom line is, you should not let diamond fluorescence unduly influence your choice when selecting a gemstone. If the industry experts can't seem to agree and constantly split hairs over the effect, then it should just be a matter of personal preference.