The Reality Of Sapphire Treatments September 04 2016
Clients from across the world who seek to purchase natural sapphire gemstones from their jewelers seem to always prefer unheated sapphires. However, this rare precious gemstone is even more so when it comes to unheated sapphires. The stark reality of its extreme rarity severely limits the color, size and shape available for clients and hence almost all purchases are made with heat-treated sapphires. In fact, gemstone treatments have been the norm for several centuries with the earliest record found in Pliny the Elder’s Natural History written in approximately 77 AD.
While there is an assortment of gemstone treatments, heat is by far the most common and most preferred method. The fundamental goal of heat treatment is to dissolve rutile inclusions within the crystalline lattice structure of the gemstone. Rutile refers to minerals composed of primarily Titanium Dioxide which act as minor blemishes of a natural gemstone such as a sapphire. Heating the sapphire to a temperature between 1,700 degrees centigrade and 1,843 degrees centigrade, the melting point of rutile, achieves two desirable consequences; the sapphire experiences an improvement to its clarity through the removal of any ‘cloudiness’ and its color is enhanced as the rutile decomposes to its structural elements and releases titanium into the lattice structure. These treatments are often reliably tested by laboratories and Gem & Jewelry Authorities and are meticulously certified before being sold.
Like inclusions, color zoning is usually regarded as a less than desirable trait for sapphire gemstones. A fine sapphire attributes itself a uniform and consistent distribution of color and a break in that smooth gradation results in a significant loss in value. Color zoning originates through the concentration of color generating trace elements during the formation of the crystal over several thousands of years. Despite being a factor for discounting value for sapphires, color zoning can often be a valuable trait for other gemstones such as amethyst or citrine. In the case of citrine, the orange hue can form through an elaborate blend of yellow and red color zoning. The natural phenomenon of color zoning can also be used to test the authenticity of these gemstones as synthetic gems are often engineered to an even color dispersion.
While some imperfections such as inclusions materially deteriorate the value of a gemstone, others such as color zoning can contribute vastly to generating value. Treatment methods such as heat are the reality of many precious gemstones such as sapphires and are incredibly important to delivering a product of nature that is minimally shaped by man but maximizes the value given to clients.