Friday, August 30, 2013

Getting to know a gem - By Nathan Swan, Bonny Eagle Jewelers

Throughout the ages, royalty has worn sapphires as a symbol of wisdom, virtue and good fortune. Sapphires are also traditionally given as a gift on a fifth and forty-fifth wedding anniversary, and in America, the blue sapphire represents the birthstone for the month of September. All Sapphires are classified as the mineral species corundum, which forms in a hexagonal crystal system. Corundum is composed of aluminum and oxygen (Al2O3), and commonly forms in a shape similar to that of a hand grenade. 

The Mohs scale is used to classify the hardness or scratch-ability of an object, and objects are rated on a scale from 1 to 10. Corundum has a hardness of 9 on the Mohs scale and is second in hardness only to diamonds. A gemstone’s hardness is determined by how well a stone’s surface will resist scratching from the point or edge of another object. The Mohs scale essentially acknowledges that only a gemstone of a higher rating or equal Mohs number could make a scratch on its surface. 

Corundum forms in basically all colors, and all color varieties of the mineral species corundum are referred to as fancy sapphires, except for red, commonly known as ruby, and of course, the well-known blue sapphire. There is also the very rare asterism phenomenon in the chatoyancy (star ruby and star sapphire), identified by the star effect or cat’s eye effect seen in round dome-shaped cabochon gemstones. 

Almost all gems contain at least a few atoms of elements that aren’t in its normal chemical formula. The different colors in these gems are most importantly caused by the presence of those impurities. Sapphires that have very little impurities appear colorless. However, different levels of iron and titanium impurities cause the light blue and dark blue of sapphires. The dark blue in sapphires transpire when iron and titanium atoms replace just two or three out of every ten thousand aluminum atoms. When chromium replaces one out of every hundred aluminum atoms the red color that defines rubies becomes visible.

The value of a blue sapphire and most gemstones is determined by its rarity and the supply and demand of the market. Gemstones, especially diamonds, are predominantly graded by what is known as the four C’s; clarity, carat weight, color and cut. Sapphires may appear opaque to transparent, and blue sapphires can appear a very light to very dark violetish-blue to greenish-blue color. 

The safest way for you to clean your sapphire is with warm soapy water. If possible, it is important to protect your sapphire by having it insured. The best way to maintain your sapphire, and any gemstone, especially if it is not insured, is by having it checked by a trusted jeweler to ensure that the prongs are properly covering and securing your gemstone and that your ring fits well. We all know how scary, frustrating and devastating it can be to lose something dear to our hearts, so please take the time to maintain, appreciate and enjoy your precious gemstones and jewelry.

Nathan Swan is the owner of Bonny Eagle Jewelers, 111 Ossipee Trail E. in Standish. Questions? Email

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