When buying blue sapphires, sapphire jewelry or any type of gemstone or gemstone jewelry it is important to know of a stones potential treatments and synthetics, and imitations. Blue sapphires, much like rubies, are commonly heat treated to improve their color and even their clarity. The heat treatment of blue sapphire is very common. It is estimated that approximately 95% of blue sapphires are treated. Heating light blue sapphires can make them a darker richer blue. Heating a dark blue sapphire can make the color a bit lighter. Heating can even remove green tones from some sapphires. Though the appearance of some sapphires can be greatly improved through heat treatment heating on its own has its limits. Most sapphires, regardless of how they are heated, will never look like top quality blue sapphire. If a marketable color cannot be achieved though heat treatment sapphires are sometimes subjected to a process called lattice diffusion. With lattice diffusion sapphires are heated nearly to their melting point in the presence of chemicals that, when proper temperatures are achieved, can actually melt or diffuse into the surface of the sapphire. Depending upon what chemical elements were used in the lattice diffusion process the enhanced blue color may only penetrate to just beneath the surface of the sapphire. Due to the extreme temperatures required for this type of process the surface of the sapphire may actually melt and re crystallize. If this occurs the sapphire needs to be re-polished and due to the shallowness of the improved color, re-polishing can cause the color of the sapphire to appear molted or patchy. With some treatments the color will penetrate much deeper in to the sapphire. Sapphires that have been treated with the lattice diffusion process are far less valuable than sapphires that have not undergone such a process. A well trained gemologist will be able to tell you if a sapphire has been treated or not.
Due to the price of fine blue sapphire, there is a big market for synthetic sapphires and sapphire imitations. Synthetic sapphires are sapphires that have been grown in a lab instead of forming in nature. There are several processes used to produce synthetic sapphire. Some processes are very fast and inexpensive. These processes can produce synthetic sapphires in a matter of hours. Synthetic sapphires produced via this method are very inexpensive sometimes costing only a few dollars a carat. Other methods can take months to produce synthetic sapphires. Sapphires produced through this type of method are of much higher quality and resemble their natural counterpart much more closely. It takes a well trained gemologist to identify these higher quality gemstones as synthetic sapphire.