The Gemological Institute of America uses the description “Blue sapphire’s hues reflect the sky’s every shade, from blazing afternoon to velvety midnight,” (GIA, Vol. 13, p. 1). The great thing about sapphires is that they come comes in every hue of the rainbow. Other sapphire colors use the term “fancy color sapphire” to delineate between the two groupings. Corundum is the name of the mineral and technically includes all sapphires, and the red variety called ruby. Corundum has many great aspects making it a very popular gemstone.
Sapphires symbolize nobility, sincerity, truth, and faithfulness. Royalty use the gem in their scepters, crowns, robes, and orbs. Many engaged couples choose sapphire instead of a diamond for many reasons, but faithfulness is a good reason. Another reason is because it is the hardest gemstone after diamond. On the Mohs scale, diamonds are the hardest mineral, ranking at a 10. Although diamonds are exponentially ten times harder, sapphires are over- achievers in hardness – 9 on the Mohs scale – and are especially tough and stable. This durability means they are a great gemstone for daily wear.
In corundum’s purest form, the gemstone is colorless, and is composed of only aluminum and oxygen. Elements, as listed in the periodic table, create the huge range of colors. To create blue, all that is needed is a trace of iron and titanium. Because the element silicon is so prevalent on earth, the absence of it to create corundum makes this gemstone relatively rare. Some popular places on earth to find sapphire are Madagascar, Cambodia, Thailand, Australia, Sri Lanka, Kashmir Providence of India, and Myanmar (formally Burma). Closer to home is in the state of Montana, USA.
As with most things earthy, sapphire has typical inclusions; among these are rutile (silk) needles, boehmite needles, included crystals (a crystal inside a gemstone), fingerprint inclusions, growth zoning, and color zoning and banding. Color zoning is the easiest to see with the naked eye and is an area where color is absent. Ninety five percent of sapphire stock is heat-treated to improve color and clarity. Stones that are not heated are either commercially undesirable or VERY desirable because they are beautiful without it. Heating provides many different results: an increase in blue coloring, a lightening of dark blue material, reduction of greenish tints, filling of fractures, removal/diffusion of titanium bearing rutile needles to improve color, clarity, and transparency, or development of rutile (silk) to induce asterism or stars (GIA, Vol. 13, p. 12).
Speaking of asterism, phenomenal corundum is quite unique. Asterism is talking about the phenomenon of creating a 4, 6, or 12-pointed star in a piece of cabochon, a smooth-topped non-faceted gemstone. Stars are created by an abundance of silk or needle-like inclusions. Another phenomenon is color-change sapphire. Under different kinds of light (daylight versus incandescent), you will see a couple of different colors emerge to varying degrees. The element vanadium causes the color change in sapphire and is considered very rare. The value of these two types of phenomena is mainly dependent on how vivid the star is and if it is centered. For color-changing sapphires, the color change is classified as weak, moderate, or strong. The stronger the color change, the more valuable the stone is. Imitations and synthetics do indeed exist, but Olufson Designs only carries the finer examples of the rare, better quality stock.
As an American Gem Society (AGS) jeweler, we pride ourselves in business ethics and education. Elisa Olufson is a Graduate Gemologist (GIA), Fellow of the Gemmological institute of Great Britain, and certified gemologist appraiser. Kendra is a Graduate Gemologist (GIA) and Certified Gemologist. Emi and Lisa have their Certified Sales Associate credentials through AGS. Although we do not know everything, we can answer most questions or be able to research them for the answer. We always boast how much we love color here at Olufson Designs, so catch the fever and gift a September birthday a lovely piece of sapphire in any color, because we have most of them!