What is the Best Color for Blue Sapphire? Part 1September 3rd, 2009 by James L. Sweaney, CGA, FGA. GG
Our clients often ask “What is the best color blue sapphire?” There are two answers– the obvious is that personal preference should dictate your color choice. Every person has unique abilities to perceive color, based on such things as age, health, culture and genetic gifts. Some people prefer light pastel colors, others prefer rich intense colors. The best color for you is the one that pleases, stimulates, or excites you!
The more complicated answer has to do with gem grading and market preferences, the physical characteristics of natural sapphires, the geological sources of sapphire including Ceylon, Burma, Kashmir, Madagascar, Thailand, Australia, and Montana, and the various methods of color enhancement and heat treatment of sapphire. We'll begin by discussing gem grading and market preferences.
Color is a very complicated phenomenon in gemstones, presenting many challenges for gemologists and gem traders. We begin by grading the color of blue sapphires in terms of hue, tone, and intensity- for a thorough discussion of color grading gems, visit the color grading page at our Gallery of Gems.
Hue can be described as the name of a color, and relates to the actual wavelength of the visible light emanating from the gem. Some gem colors are described as two hues– such as green blue, signifying equal parts green and blue, or greenish blue for a color proportionately more blue than green. In grading gem colors, we normally emphasize the dominant hue by capitalizing it. For blue sapphire, the perfect hue would be simply Blue– not greenish Blue or violetish Blue. The hue of the sapphire below would be described as very slightly violetish Blue, while the hue of the second stone shown below and the blue sapphire ring shown at the beginning of this article is Blue.
Tone is the relative position of a color on a 1 to 10 scale of light to dark. 1 being white, 10 being black. Blue sapphires can range from very pale blues that might be graded 2- 3 on the tonal scale to extremely dark blues that are graded 9. The 4.5 ct. Ceylon sapphire in the estate ring shown below is somewhat light in tone, ~ 4. The preferred tone for most blue sapphires that are used in jewelry is generally about 5 – 8.
Intensity is sometimes referred to as vividness or color saturation. There is an optimum combination of saturation and tone for each hue known as the gamut limit. Yellow colors are most vivid in the tonal range of 2-3, greens around 7, reds and blues around 7-8. Over about 85% tone, blue colors rapidly lose intensity– many commercial grade sapphires are so dark they appear “inky.” We grade intensity on a scale of 1 to 6, 1 being brownish or grayish colors, 6 being Vivid colors.
Intensity is the one characteristic that really separates the very best blue sapphires from all the rest. Stones that are truly “vivid” stand out– for example, one to two carat “vivid” stones may be double or triple the value of stones graded “strong.”
So, in terms of gem grading and market valuation, the color of the highest grade and most expensive blue sapphires will have a hue of Blue, a tonal range of 7 to 8, and Vivid saturation. Although color is the dominant factor in grading and valuing blue sapphires, clarity and cutting are also very important, especially in those over one carat. The best blue sapphires have the perfect color, high transparency, and great craftsmanship of cutting.
In parts 2,3, and 4 of this series, we'll discuss the role of the physical nature of sapphire, the geological distribution of sapphire, and the impact of enhancements on the color of blue sapphire.
If you're in the market for this wonderful gem, stop by our shop, visit our Gallery of Gems, or give us a call — we'll be happy to search the markets to locate your perfect blue sapphire!