How to see if a Diamond is real

Looking at the stone's refractivity:

Diamonds sharply bend, or refract, the light that passes through them, resulting in their strikingly brilliant appearance, they do not absorb light but actually reflects it back out. Stones like glass and quartz sparkle less because they have a lower refractive index and they absorb the light that goes into them. The inherent property of the stone cannot be altered, so even an expert cutter can’t enhance a stone’s brilliance. 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.

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If the stone is not set in a setting and you are able to handle it, here are a few ways to see if a diamond is real:

  • The line test:Turn the stone upside down and place it on a straight drawn line on a piece of paper. The line must go exactly through the middle of the upside down diamond. If you can see the line through the stone, even if the line is bent, then it probably isn’t a diamond. A well cut diamond would bend the light so sharply that you wouldn’t be able to see the line. (There are a few exceptions: if its cut is disproportionate, meaning it is cut too deep or too shallow, the print can still be visible through a real diamond.)
  • The dot test:Draw a small black dot with a pen on a piece of white paper and place the stone upside down and directly over the centre of the dot. Look down on it. If the stone is not a diamond, you will see a circular reflection in the stone. The dot will not be visible through a real diamond.
  • The girdle test: All stones have girdles: that is the outside “rim” of the stone. Once again place the stone upside down on white paper, if you can see a definitive ring on the outside of the stone it is probably an imitation stone. Once again the light through a well cut diamond will reflect out, whereas with an imitation stone it absorbs the light and concentrates on the girdle.

How to see a diamond is real If it is set in a piece of jewellery:

Use the breath test: Put the stone in front of your mouth and breathe on it like you would do with a mirror. If the stone stays fogged for a couple seconds, it is most probably a fake — a real diamond will disperse the heat from your breath instantaneously and won’t fog up easily. Even if you do this repeatedly and wait in between fogging it up and looking at it, it will still clear much faster than a fake.

We suggest you test this on a stone you know to be a real diamond first so that you can watch how the real one stays clear while the fake one fogs over; if you breathe on imitation stones repeatedly, you will see condensation start to build up. With each breath, the fake stone will fog up more, while the real one will still be clean and clear.

Check the setting and mount: A real diamond would most likely not be set in cheap metal As per regulation, all jewellery items should have stamps inside the setting indicating real gold or platinum (9CT, 14CT, 18CT, 375, 585, 750, 900, 950, PT, Plat) are a good sign, while a “C.Z.” stamp is a dead give-away that the centre stone is not a real diamond. C.Z. stands for Cubic Zirconia, which is a lab grown stone that looks like a diamond. The general rule is also that a ring stamped SIL or 925, which is Sterling silver, would not be set with diamonds, but rather Cubic Zirconia.

If you are still uncertain, please bring the stone into Your Diamonds for viewing by our experts.

We have strong magnification Loupes that we use to view the inside of the stone.

Each diamond has its own unique characteristics that we look for.

Mostly this will be small to obvious natural inclusions that give your diamond its own classification. Under the Loupe magnification we can also pick up rainbow colours in the diamond which you would not find in a clear cubic zirconia. They are completely colourless.

In the extreme 1% of cases if both of our diamond experts are not convinced of your stones characteristics, and the stone is in a setting, we will ask to remove the stone under your supervision to view it in its natural unset state.