Diamonds sharply bend, or refract, the light that passes through them, resulting in their strikingly brilliant appearance. Stones like glass and quartz sparkle less because they have a lower refractive index. A stone's brilliance is difficult to alter in any way, even with an expert cut, because it's an inherent property of the stone. By taking a close look at the stone's refractivity, you should be able to tell whether it's the real thing or a fake. Here are a few ways to do it:   The newspaper method: Turn the stone upside down and place it on a piece of newspaper. If you can read print through the stone, or even see distorted black smudges, then it probably isn't a diamond. A diamond would bend the light so sharply that you wouldn't be able to see the print. (There are a few exceptions: if its cut is disproportionate, the print can still be visible through a real diamond.)  The dot test: Draw a small dot with a pen on a piece of white paper and place the stone over the center of the dot.  Look directly down on it. If your stone is not a diamond, you will see a circular reflection in the stone. You won't be able to see the dot through a real diamond. A real diamond's reflections usually show up in various shades of gray. Look straight down through the top of the diamond. If you see rainbow reflections, you're either dealing with a low-quality diamond or a fake.  Instead, check for "sparkles." A real diamond will sparkle significantly more than an equivalently-size piece of glass or quartz. You may want to take along a piece of glass or quartz as reference. Don't confuse sparkle with reflection. Sparkle has to do with the brilliance or intensity of the light that's refracted by the cut of the gem. Reflection has to do with the color of the light that's refracted. So look for intense light, not colored light. There is a stone that has even more luster than a diamond: moissanite. This gemstone is so similar to diamond that even jewelers have a hard time telling them apart. To tell the difference without special equipment, hold the stone close to your eye. Shine a penlight through the stone. If you see rainbow colors, that's a sign of double refraction. This is a property of moissanite, but not of diamond. Due to its high density, a real diamond will sink. A fake one will float at the top of the surface or in the middle of the glass. Heat up a suspect stone with a lighter for 30 seconds, then drop it straight into a glass of cold water. The rapid expansion and contraction will overwhelm the tensile strength of weaker materials like glass or quartz, causing the stone to shatter from the inside. Real diamond is strong enough that nothing will happen.
لاحظ الانكسار النوعي للماسة. ملاحظة الانعكاسات. ضع الماسة في كوب من الماء ولنرى هل ستغوص للقاع. قم بتسخين الماسة وانظر هل ستنكسر.