A very important factor when purchasing a gemstone is an understanding of the treatments subjected to a stone and how those treatments affect value.
For centuries many sapphires have been exposed to heat, in an effort to improve what nature created. In the 19th century, pale imperfect sapphires were heated to heal inclusions and remove all color, rendering the stone transparent and colorless. These transformed stones would then be used as diamond stimulants. By the mid 20th century, the same pale material previously heated to become colorless, was being treated with improved technology. To deepen stones to a more desired blue color, they are subjected to extreme high temperatures and exposed to titanium and iron in a controlled environment. Although this remains a somewhat unpredictable process, the desired result can transform pale sapphires into the finest colors possible in nature.
Many other modern treatments are applied to sapphires including beryllium coatings, which apply a thin layer of color to the stone. There are many other lesser-used treatments, such as fillers used to improve clarity.
Some treatments alter the natural crystal structure and can destroy internal inclusions. When a stone has been compromised, gemologists can identify the damage by reading altered internal characteristics. While these treatments do make insignificant material more marketable, treatments actually have a negative effect on value when compared to their natural counterparts. Ultimately, the treatments are creating an abundance of new material that is pretending to be precious and rare
The staggering truth is, roughly 90 percent of the sapphires on the market today have been treated in some way. This makes understanding treatments extremely important for the buyer and collector. The difference in the true value between a treated and untreated gemstone is substantial.