Often associated with royalty and faithfulness, sapphires are the quintessential blue gemstone. Sapphire is the 3rd most popular stone – diamond and pearl are first and second, respectively – in the world. With sapphire engagement ring of Kate Middleton, this magnificent gemstone will only gain more popularity in the coming years. As such, this buying guide should help those looking to add sapphires into their collection.
Although known for the stunning blue color, sapphire can be a wide range of colors – colorless, violet, purple, green, yellow, orange, pink, gray, brown, and black – called fancy sapphires. Blue is best known and most valuable. Pink, orange, and yellow colors are gaining popularity these days. Green is the most numerous and least valued while gray or brown are not desired. Pure colorless sapphires are quite valuable but rare without contamination; popular as small accents in jewelry and a substitute for diamond.
Unlike diamonds, color intensity is the most important factor in valuation. Factors that determine the overall color are hue, tone, and saturation. Hue is shade of the color, tone represents how light or dark the stone looks, and saturation measures the strength of the color from dull to vivid. Best viewed under sunlight; artificial or incandescent light may make the stone appear redder and less attractive.
When buying a sapphire, strong saturation is preferred, and most important factor, but must not hinder the brightness of the stone. Next, medium to medium dark tones are preferred; light tones will make the stone appear washed out but do have greater brilliance. Dark tone stones are abundant and inexpensive.
For blue, rare Kashmir and Burmese sapphires with intense, deep blue or violet-blue and velvety luster are the most sought after. Stones from these regions can possess the desired “cornflower” blue, also known as Kashmir blue. Yogo sapphires from Montana are dazzling collectors recently with beautiful Kashmir-like quality. For example, a high quality 1-carat Kashmir sapphire can cost about $22,000 while a similar purple sapphire will cost about $570.
Although pink diamonds have overtaken pink sapphires in recent years, pink sapphires are still a popular color and, importantly, cheaper than diamonds. Of the shades of pink, hot pink is the most sought after from Burma and Sri Lanka due to its intense and vivid color.
Fine yellow sapphires are yellow to orange-yellow with vivid saturation. Similarity, quality orange sapphires range between strong orange to red-orange with medium tone and vivid saturation.
An extremely rare, and expensive, unique shade of pink is Padparadscha from Sri Lanka. Padparadscha is described to be pinkish-orange to orange-pink that resembles the color of a lotus flower, salmon, sunset, or ripe guava; a hint of pink should always be noticeable. Good quality stones with intense saturation can demand about $20,000 per carat.
In addition, some sapphires can display pleochroism, or color change under certain lighting and angles. Blue can change to violet under daylight or fluorescent light. Violet-purple stones can turn to reddish-purple under incandescent light. Although rare, some green stones can change to a reddish-brown under incandescent light. The stronger the color change, the more value the stone can demand.
Ranging from transparent to opaque, transparent is the most desired clarity for the beautiful luster. Opaque stones are fairly inexpensive.
Like most colored gemstones, eye clean is enough for the high marks; this is due to the fact that majority of colored gemstones contain inclusions of some sort like liquid, gases, and other crystals. Buyers should be cautious if the stone looks perfectly clean, it is likely to be fake. Using the same 1-carat Kashmir example from above, the same stone with inclusions can bring the price down to $9,000.
Additionally, many of the special characteristics of sapphire are caused by inclusions, especially silk-like needle structure called rutie. The famous Kashmir velvety appearance is due to the scattering of light by extremely fine rutie needles throughout the crystal structure. Too much rutie, however, can weaken the lustrous color and turn the stone towards the gray spectrum.
Speaking of, rutie needles are also responsible for asterism in star sapphire. The rutie needles must be properly aligned, about sixty degrees, in the same direction to form the six to twelve, commonly six, rayed star under strong light. For black star sapphires, hematite is responsible for asterism in the gemstone.
When buying star sapphires, look for an uniform, crisp star against a strong saturation – lighter saturation will lower the visibility of the star – and semi-transparent clarity. Blue star sapphires are the most valuable. The star should be visible at arm’s length and at all directions; elegantly gliding as you rotate the stone without dead spots.
Common cut styles are rounds, ovals, pears, and cushions. Round diamond-cuts are usually the most desired and commands a high price. However, emerald and marquise cuts can maximize the light reflection and improve the color; these cuts can be quite expensive when expertly cut.
Translucent and star sapphires are often cut into beads or cabochons.
Heat treatment is common for sapphire; most stones on the market today are heat treated. As such, untreated sapphires with rich blue are very expensive. Heat treatments removes some inclusions like tiny rutie needles and improves color tone and saturation.
Diffusion treatment involves applying a thin layer of dye to the surface of the gemstone. This treatment is usually done to star and blue sapphires.
Beryllium treatment is used to produce brilliant orange sapphires. This treatment can turn some light color orange or yellow stones to a Padparadscha-like color.
Synthetic sapphires are very abundant due to the fact that sapphire has many industrial uses due to the hardness of the stone. Keep in mind that even though they are called synthetic, lab created sapphires are actual sapphires, chemically and physically. Only experts can tell them apart, but the big hint is the lack of any inclusions compared to the real thing. Buying from reputable sellers is recommended.
Because sapphires have such a high hardness, 9 on the Moh’s scale, caring for them is easier than other gemstones since they are more resistant to scratches. However, care still should be practiced. To clean them, use a soft cloth or brush with soapy water and rinse well.
Avoid harsh cleaning agents, like bleach and hydrofluoric acid, as these can be corrosive to the stone.