Sapphires - Synthetic or Real

With scientific advancements comes the potential to run into more and more convincing synthetic stones.
How can you tell the difference?
The most effective way to tell the difference is in their Refractive Index of the natural stone. Also all stones formed from the earth will have some inclusions. 
Specific Gravity is not helpful in determining a synthetic from a natural stone.




3 simple tools together -- Loupe, Chelsea filter, and Dichroscope -- which are also useful in the field. And if you have a portable LW/SW UV lamp, that's also an important tool. For example, garnet is single-refracting and will show no dichroism (with a dichroscope, a dichroic stone will show one color in one window, and a different color or different "shade" of color in the other window of this small instrument). So this will immediately separate a garnet, glass or synthetic SPINEL imitating another gem from ruby, sapphire or emerald. In terms of tsavorite, when viewed through the Chelsea filter, tsavorite will appear reddish, but green glass or syn green spinel will NOT. Tsavorite is SINGLE refracting so it will show the same color in each window of the dichroscope, but some of its imposters (syn corundum) are double refracting and show dichroism, but in any event, those stones do not go red through the Chelsea filter. And then, the loupe will show inclusions in tsavorite that you will never see in glass, syn spinel, and so on. Natural, untreated blue sapphire will usually show no fluorescent reaction (under either wavelength) whereas treated-blue sapphire usually shows a blue/white reaction and synthetic blue sapphire will have a stronger reaction, and even stronger under short-wave. And so on. There is never just one test that will tell you what you need to know....it's a matter of collecting the "clues" from information provided by at least a couple of tests, and putting the pieces of the puzzle together.
Do you have my book "Gem Identification Made Easy" (published by Gemstone Press -- www.gemstonepress.com)? I talk about how to use a variety of instruments, and explain how valuable small, portable tools can be when you know how to use them PROPERLY, and when you use them together to collect the "clues" you need.