A sapphire is a precious stone that is usually deep blue. Properly cut sapphires have beautiful facets that catch light and create a glow much like a diamond. Because synthetic sapphires look so much like the real thing, it may be impossible for you to tell they're not natural unless you use special tools. If you're in the market for a real sapphire, it's important to be sure you're not getting something created in a lab.
Examine the gem carefully for inclusions (flaws) that are in the shape of bubbles. You may need to use a jeweller's magnifying glass to see these small imperfections. If you think you see some of these inclusions, use a flashlight to shine a light directly on the gem. If there are bubble-shaped inclusions, they will disrupt the light from flowing through the facets of the gem as it should.
Test your gem using fibre-optic lighting. The fibre optic lights will shine through some of the chemicals used to make a synthetic sapphire, creating an abnormal light display. A synthetic sapphire will have more of a red hue under the fibre-optic lighting.
Rub the gemstone between your hands. If the gem creates a slightly waxy feeling, the stone may be synthetic. A natural sapphire will feel smooth and hard in your hands.
Ask a jeweller if he can examine the sapphire for you. As a professional, he is knowledgeable about many gemstones and should be able to tell if the sapphire is synthetic or natural. Jewellers also have the special tools necessary to determine if the gem is synthetic. If you believe your sapphire may be synthetic because you see flaws, do not be overly concerned. This is normal for both synthetic and natural gems. The most common flaw is feathering, which means there are small cracks on the inside of the gemstone. These flaws occur when the sapphire forms under extreme pressure, and it can happen to both synthetic and natural sapphires.