 How to tell if a ruby is real? Rubies can be the most valuable colored gemstone, based on price per carat. When, however, there are a lot of fakes out there, and it can be hard to tell if a ruby is real. Ultimately, the surest way to tell is to take the stone to a licensed jeweler. At home, you can gauge the ruby's authenticity by looking at its color and its hardness. Use a 10-power magnifier, if possible, to inspect the ruby up close. Inspecting the ruby at home. Tell by the color and the shine. Real rubies glow with a deep, vivid, almost stoplight red. Fake gems are often dull, they are light, but not bright, if the gem is more of a dark red, then it may be garnered instead of a ruby. Check for a consistent and even color throughout the stone. Fakes are more likely to contain blemishes and impure spots. That said, rubies do sometimes have imperfections. Use that stoplight red as a guide, but do not expect to find a real ruby that is actually that bright. If you do, then the ruby is likely fake. A real ruby should be more like a bright traffic light, however, than like a dull stone. 4. Compare the ruby stone to a shard of red glass. Rubies and other varieties of sapphire are often faked as glass. If the glass and stone look similar, then you may just be holding two pieces of red glass. Try to scratch the surface. Real rubies are extremely hard stones. Grind a fingernail or a coin into the surface of the ruby and see if you are able to scratch it. If the ruby shows a scratch, then there's a good chance that it is not a real ruby. Only a diamond can scratch a ruby. Composite rubies are not as durable as real rubies. There is a chance that the ruby is not a complete fake, and just a machine made stone, 8. See if the ruby rubs off on another surface. Gently scratch the stone against a hard, smooth surface, porcelain tile or a piece of clear glass. The stone should scratch the surface whether or not it is a ruby.The tip off, however, comes if the ruby leaves a red mark on the surface where you scratched it. The red mark might be a sign that the gem is artificially colored. It might tell you that the gem, is actually made from a much weaker material. Know the types of fake. The stones commonly used as ruby imitations include garnets, tourmaline, glass, and composite gems. Garnets are dull, dark red silicate minerals. They are much softer than a ruby. Tourmaline is a reddish pink silicate mineral. Tourmaline is somewhat harder than a garnet, but much softer than the ruby. Red colored glass imitations are usually cheap, but not very durable. It should be easy to tell if a ruby, is actually made from glass. Composite rubies are real rubies that have been fused with glass. This makes the stone larger so that a jeweler can sell it for more money. Beware. Composite rubies are often sold as real rubies, for real ruby prices, 11.