Sapphires are beautiful, durable, natural gemstones that come in many brilliant colors making the sapphire for engagement rings and other fine jewelry an ideal choice as a center piece.
Sapphire Color Choices
Sapphire is a variety of corundum made of aluminum oxide. Although the blue sapphire is the most popular corundum variety, colors such as peach, yellow, orange, green, pink and a mix of these colors are also found naturally. The peach sapphire for engagement rings has become the number one choice in recent years. Sapphires even come in red, which is a category on its own, the ruby. There are a number of treatments that have been developed and used to improve the various colors of sapphires, which are discussed below.
“Fancy sapphire” is a general term applied to any sapphire other than blue sapphire or ruby.
Small traces of minerals or impurities, also called “color centers” are responsible for the different colors in sapphires. For instance, chromium is the mineral in corundum which contributes to the red color in ruby and iron gives the blue color in corundum known as blue sapphire.
A white or colorless sapphire for engagement rings has become the alternative choice to diamonds, and color change sapphire has become the economical alternative to alexandrite (considered one of the most expensive gemstones in the world). White sapphire is the only variety of corundum that is considered pure or free of impurities hence its colorlessness. Color change sapphire is perhaps one of the most interesting of corundrums due to the color change under different lighting conditions. Color change sapphires go from blue color in daylight to purple under incandescent light. The more dramatic the change in color, the rarer it is to find, and hence, a greater premium is charged.
Sapphires are 9 in hardness on the Mohs scale. Only diamonds are harder than sapphires (at a hardness of 10). Although, diamonds are harder than sapphires, they are actually not as tough as sapphires due to what is called “perfect cleavage”. A hard enough blow can break a diamond along its cleavage. Toughness is the ability to withstand a blow and hardness is the ability to resist scratching. This is another reason why I highly recommended the sapphire for engagement rings over many other gemstones; not just for their beauty and variety in color, but also for their durability during daily wear.
Sapphires can undergo many different treatments but by far the most common and well accepted treatment is heat treatment. Heat treatment is basically an extension of what occurs in the natural formation of gemstones (heat & pressure). The main purpose of heat treatment is to improve clarity and color of the gemstone even though there is no alteration to the gemstone’s physical and optical properties. It is said that over 95% of all sapphires on the market today have been heat treated. It is important to stress that heat treatment is 100% stable, and generally only causes subtle improvements in color and clarity.
Non heat treated sapphires are marketed as such, and there is a premium to be paid for such sapphires. A buyer needs to be cautious about purchasing what is claimed to be a non heat treated sapphire, as there are many false claims about such sapphires, and the difference can be very difficult to detect even by a trained professional. Anyone wanting to purchase what is claimed to be a non heat treated sapphire will want certification from a reputable 3rd party to ensure that it is indeed not heat treated.
Diffusion and beryllium treatment are other treatments used in sapphires. Beryllium treatment is done by introducing chrysoberyl during the heat treatment process to create a change in color of the sapphire. Beryllium treatment is also a stable treatment.
Diffusion treatment on the other hand is not 100% stable. Diffusion treatment is done by adding chemical agents during the heating process. It is important to mention that eventually if the gemstone needs to be repolished, part of its color could be removed since this treatment penetrates only a few millimeters deep into the gemstone. Since beryllium or diffusion treatments rely on introducing agents to dramatically change the gemstone’s color, they are required by the industry to be disclosed by the seller.
Choosing the right sapphire:
When choosing the right sapphire for engagement rings, there are a number of factors that should be taken into account. Two factors that impact all of us are personal; preference and price. Price of gemstones and personal preference are impacted by four different factors, which are color, clarity, carat, and cut. There are also external factors that may affect a gemstone’s value such as jewelry trends, seller’s mark up and ultimately the gemstone’s supply and demand.
Color can account for up to 50% of the price of a gemstone, so it is considered one of the most important factors. Pure colors command a higher price so any secondary colors would reduce the gemstone’s value accordingly to the degree of its deviation from a pure color.
Secondary colors in rare cases could be a positive thing such as a pinkish orange sapphire known as a Padparascha sapphire, which command the highest price for their sought after color.
In most cases a blue sapphire, with a hint of gray, purple or green will cost substantially less than a pure blue sapphire.
Sapphires are relatively rare and fall into the category of a Type 2 Gemstone, which means the condition in which they are formed in nature is not always favorable, so some inclusions should be expected especially in gemstones over 1 carat in size. As long as the inclusions are not detrimental to the beauty of the gemstone, then they do not have a great impact on price, and should not be a great concern to the purchaser. As a matter of fact, inclusions are part of a gemstone’s natural identity and certainly distinguish them from less valuable man-made sapphires, which are free of inclusions.
Cut is often overlooked, but a well cut gemstone will make its color more uniform throughout the gemstone, and it will contribute to its higher brilliance when compared to improperly cut gemstones, which only partially reflect light.
One of the characteristics of Ceylon sapphires is color zoning or natural bands of blue color, which can be reduced or eliminated if they are cut at their correct refractive index (the angle in the bottom of the gemstone responsible for 100% of light reflection).
Another component of cut is the actual shape. Demand for certain shapes has an impact on price, but so does the practical nature of retrieving a fine gemstone from a rough piece of stone. It is more efficient (less waste of precious material) to retrieve an elongated shape without corners from a rough piece of stone than a square shape with corners. Therefore, oval shapes tend to be the most economically priced compared to square, square cushion and round.
The gemstone size or carat weight can amplify the importance of every single gemstone evaluation component (color, clarity, cut) many times over. Good quality sapphires in larger sizes are rare, so as the size increases, pricing often increases exponentially.
Sapphire is perhaps one of the oldest gemstones treasured by many and worn among kings and queens. The word sapphire has its origin in the Latin word sapphirus.
Sapphires are found in many different countries such as Sri Lanka (formerly Ceylon), Burma (Myanmar), Thailand, Cambodia, Madagascar, Tanzania, Australia, and even in the U.S. (Montana sapphire). There are certain characteristics found in sapphires inherent to their source (location) such as color, as well as some particular types of inclusions (any material that is trapped inside a mineral during its formation). In fact inclusions are the best clue to identify a gemstone’s origin. The best sapphires come from Myamar, Sri Lanka (Ceylon), and the Kashmir region of India, but little material or almost none are found in Kashmir today.
When you purchase a beautiful, genuine sapphire, it is something that has been created by the hands of nature, it is one of a kind, and something to be treasured.
Another useful resource on sapphires, would be the Gemologicial Institute of America encyclopedia page on sapphires.
Blog prepared by: Rogerio Graca, professional gem cutter/lapidary and supplier of gemstones for 24 years. Read All About Us!