Introduction and Overview:
Blue White Diamonds
“…the never failing test for correctly ascertaining the water
is afforded by taking the stone under a leafy tree and in the
green shadow one can easily detect if it is blue.”
Jean-Baptiste Tavernier, 1689
Historically the finest colorless diamonds have been known as blue whites. Beginning in the 1970s diamonds so described began to fall out of favor. This is due to a misunderstanding in the trade as to the precise definition of the term and the difficulties involved in grading gems so defined.
In modern times, a blue white diamond has come to be defined as a colorless diamond that fluoresces blue in ultra violet light1. Historically this was not the case. The original blue white diamonds were the legendary Golconda diamonds of India. Unlike most diamonds available today, many of these gems fell into a very rare category of diamond known as type IIa. Type IIa diamonds are characterized by a lack of Nitrogen impurities in the crystal lattice, a white to bluish body color and the fact that they do not fluoresce in ultra violet light. One percent of the world’s diamonds are type IIa and the other ninety nine percent are type Ia.
Type Ia diamonds do contain Nitrogen which is the cause of their slight yellowish body color and fully one third of type Ia gems fluoresce blue under UV light.
In the mid to late 17th century, Golconda was a small sultanate located in the modern Indian State of Andhra Pradesh about seven miles from Hyderabad. Golconda was a diamond-trading city. The closest diamond mines were situated five days by horseback at Rammalakota a village about twenty miles south of Karnul. Another mining center, Kollur, was a leisurely seven-day journey east of Rammalakota. The diamonds traded at Golconda could have come from either of these mines or from half dozen or so mining locations further northwest. No one knows what percentage of old Indian diamonds traded at Golconda were type IIa, but many of the celebrated colorless diamonds that survivein museum collections with demonstrated Golconda provenance, including the Koh-e-Nor, Regent and, Beau Sancy, are type IIa.
Not all type IIa diamonds were sourced from India. Type IIa diamonds have been found in Brazil and continue to be mined in southern Africa. The diamond mines of India and Brazil were worked out in the 17th and 18th centuries respectively and most diamonds in the market today that hail from Africa, Canada and Russia. Ninety nine percent of these are the more commontype Ia.
Due to the paucity of Nitrogen, type IIa diamonds exhibit a snowy white and some exhibit slightly bluish body color2. Gems of this type are also known for their exceptional transparency or crystal. Given the lack of UV fluorescence, the source of the bluish body color2 in type IIa diamonds is not well understood3. Historically, highly transparent diamonds with white and bluish white body color were considered gems of the finest water, a rare quality known as river. In the late 19th century, fully one hundred years after the Indian mines were tapped out and with production from Brazil slowing to a trickle, diamonds from southern Africa began to flood the market. Some of these were blue fluorescent diamonds. According to the legendary gemologist, Frank Wade, writing in 1915, those that did not bleed color, that is, did not appear yellowish face up in the low ultraviolet of incandescent light were added to the river category4.
Blue and yellow are what is known as complimentary colors. Complimentary colors nullify each other. Blue ultraviolet fluorescence will cancel out the yellow in a diamond’s body color, resulting in a stone that appears “whiter” (less yellow) in natural daylight. Unfortunately the vast majority of blue fluorescent gems will exhibit a slight yellowish body color when viewed in incandescent or LED lighting. The color grade is dependent upon the type of lighting used. For this reason blue fluorescent diamonds cause a great deal of trouble for the professional grader5.
During the hard asset investment craze of the late 1970s, investors insisted that diamonds they purchased came with a laboratory report from The Gemological Institute of America (GIA-GTL). Thousands, sometimes tens of thousands of dollars, rode on the color grade given a diamond on the laboratory report. Investors paying high prices often insisted on resubmitting their stones and nervous graders subsequently downgraded strongly fluorescent stones that faced up better than their facedown grade6. This is set off something of a controversy within the trade.
GIA formerly taught that diamonds should be graded under low UV lighting. That opinion was reversed in 2008 when the institute decreed that diamond grading should be carried out in light7 with some ultraviolet because ultraviolet is a constituent of natural light. Others, most notably The Accredited Gemologist’s Association (AGA), maintained that light with UV filtered out should remain the standard particularly when grading blue fluorescent diamonds. Don’t let your D become a G. In actual experiments conducted by AGA, fluorescent diamonds have been shown to bleed, add enough yellow to reduce the color by as much as four grades when evaluated in low UV lighting8.
In 2000 GIA-GTL adopted a new grading methodology and a new grading environment using two Verilux F6T5 fluorescent tubes in a small box called DiamondDock. They also changed the grading methodology, increasing the viewing distance between the gem and the light source. This substantially reduced the effect of the UV in the lamp on the diamond being graded, effectively reducing overgrading of blue fluorescent diamonds from four to two color grades.
Following GIA’s lead, most laboratories have adopted similar lighting, which still results in consistent “overgrading” of strong to very strongly fluorescent blue diamonds and as a result blue fluorescent diamonds continue to be priced at a discount in the wholesale market.
What does this mean for the connoisseur? Type IIa diamonds can be easily separated from type Ia by a gemologist using a simple test. Strongly fluorescent diamonds should probably be avoided. However, some blue fluorescent diamonds do not bleed color when the lighting environment is shifted from low UV fluorescent grading light to natural daylight. These together with type IIa’s are the true blue-white diamonds. Paradoxically, due to commercialization coupled with the evolution of the term blue-white, dealers rarely test smaller diamond in their stock. River quality stones are very rare, but these original blue white type IIa’s and blue fluorescent diamonds that hold their color are well worth the seeking and likely to be priced well below their true value.
1. According to Federal Trade Commission Guideline, it is an unfair trade practice to characterize any diamond with any trace of color other than blue or bluish as blue white.
2. Frank B. Wade, Diamonds, A Study of the Factors That Govern their Value, Putnam & Sons, N.Y., 1915. P.16. Frank Wade was one of the first American diamond experts. He was a member of the GIA Student Advisory Board. In 1936 Wade became one of the first honorary members of the Institute. In 1947 GIA founder Robert Shipley inducted Wade into the “Committee of 100 World Gem Authorities.”
3. Lenzen, G., Lapworth P. B. trans., Diamonds and Diamond Grading, Butterworths, 1983, p.12
4. Wade, ibid.5. Under FTC guidelines, the use of the term “blue-white” is considered an unfair trade practice if the stone “shows any color or any trace of any color other than blue or bluish” under north daylight lighting (23.14). Thus it would seem that any diamond graded below F on the GIA-GTL colorless scale legally cannot be termed a blue white.
6. Diamolite, the light tube used since the 1950s for diamond grading by GIA, was designed to have low ultraviolet emissions to avoid stimulating fluorescent stones. However, due to a change in manufacturers, bulbs made since the early 1990s actually emit a good deal of ultraviolet light. Fluorescent diamonds graded between 1990-2000 are likely to have received a higher color grade than the same stone graded a decade earlier. Grading experiments using filters to screen out ultraviolet produced by Diamolite bulbs have resulted in downgrading of color on an average of between one half and one and one half color grades. See Thomas E. Tashey, “The Effect of Fluorescence on the Color Grading & Appearance of White and Off White Diamonds,” The Professional Gemologist, vol. 3, no. 1, Spring/Summer 2000, p. 5.
7. John M. King, et al., Color Grading “D-To-Z Diamonds at the GIA Laboratory, Gems & Gemology, The Gemological Institute of America, Winter 2008, p. 304. GIA spokesman have actually claimed that a low UV environment “doesn’t really exist anywhere,” Of course it does, every night when the sun goes down and we turn on the interior incandescent and/or LED lighting. See also: AGA Executive Summary, Lighting and Its Effect of Color Grading Colorless Diamonds…2009. http://accreditedgemologists.org/lightingtaskforce/ExecSummary.pdf