Blue Sapphire: The Complete Guide (Meaning, Price & Origin)
Marie6/7/2026
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There are several tricks for telling a real diamond from a fake with the naked eye. They can give you useful clues, raise suspicions or confirm doubts, but bear in mind that none of them allows for a definitive identification.
Before looking at how to identify a real diamond, it is worth remembering that this exceptionally hard stone (Mohs scale: 10), with its magnificent brilliance, can only be authenticated through a precious stone appraisal carried out by a professional gemmologist — or by purchasing a diamond that comes with its laboratory certificate.
To identify a diamond with the naked eye, try the light test. It simply involves observing how the stone reflects light. This trick is reasonably effective at detecting stones known as moissanites (SiC). It is less reliable when it comes to zirconium oxides (ZrO₂), which have a brilliance and “fire” quite similar to that of diamonds. Fire is the dispersion of light into spectral colours, rather like a rainbow — and in moissanites it is more pronounced than in genuine diamonds.
Diamond imitations are most commonly zirconium oxides — widely available synthetic stones that mimic the appearance of diamonds convincingly, yet cost far less.
Although popular, the breath test is the least reliable of all the small tests one can carry out at home. A 10x loupe is a better option: it can reveal whether the stone is chipped or scratched, in which case it is unlikely to be a genuine diamond. And even though diamonds are extremely hard, do not attempt to scratch glass with a stone to test it.
With a 10x loupe, you should already be able to see whether any small inclusions are present. These are rarely found in synthetic diamonds, yet are common in natural ones. The same principle applies when identifying a sapphire.
More generally, while it certainly cannot reveal everything, a loupe is a useful tool for identifying a precious stone.
Also on our blog: how to propose?
It is extremely difficult to identify a rough diamond as distinct from a synthetic one, as the two look very much alike. In fact, it is even harder than telling a genuine cut diamond from a fake. Call on our gemmology service in Angers or Paris, and we can help you obtain a certificate if you are in possession of a genuine diamond.
Useful to know, however: a genuine rough diamond is never perfectly symmetrical, unlike certain imitations. A real diamond will not normally float in water and will sink quickly, whereas fake diamonds tend to be lighter — though this is not always a reliable method.
Also worth reading: how to identify a ruby.
To identify a diamond ring, some people are lucky enough to find paperwork identifying the materials, most importantly the certificate of authenticity. Failing that, the way light disperses through the stone can sometimes resolve doubts, as it is truly characteristic of a genuine diamond.
The stone seems to shine from within, its light appearing to bounce across every facet, and depending on the lighting conditions, it takes on a different character altogether.
It is a magnificent, almost living phenomenon, and it is precisely what makes diamonds such exceptional stones. But to reliably identify a fine diamond on a ring — or unmounted — as opposed to a zirconium or any other stone, synthetic or natural, it is best not to rely on first impressions and to seek a professional appraisal instead.
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There are several tricks for telling a real diamond from a fake with the naked eye. They can give you useful clues, raise suspicions or confirm doubts, but bear in mind that none of them allows for a definitive identification.
Before looking at how to identify a real diamond, it is worth remembering that this exceptionally hard stone (Mohs scale: 10), with its magnificent brilliance, can only be authenticated through a precious stone appraisal carried out by a professional gemmologist — or by purchasing a diamond that comes with its laboratory certificate.
To identify a diamond with the naked eye, try the light test. It simply involves observing how the stone reflects light. This trick is reasonably effective at detecting stones known as moissanites (SiC). It is less reliable when it comes to zirconium oxides (ZrO₂), which have a brilliance and “fire” quite similar to that of diamonds. Fire is the dispersion of light into spectral colours, rather like a rainbow — and in moissanites it is more pronounced than in genuine diamonds.
Diamond imitations are most commonly zirconium oxides — widely available synthetic stones that mimic the appearance of diamonds convincingly, yet cost far less.
Although popular, the breath test is the least reliable of all the small tests one can carry out at home. A 10x loupe is a better option: it can reveal whether the stone is chipped or scratched, in which case it is unlikely to be a genuine diamond. And even though diamonds are extremely hard, do not attempt to scratch glass with a stone to test it.
With a 10x loupe, you should already be able to see whether any small inclusions are present. These are rarely found in synthetic diamonds, yet are common in natural ones. The same principle applies when identifying a sapphire.
More generally, while it certainly cannot reveal everything, a loupe is a useful tool for identifying a precious stone.
Also on our blog: how to propose?
It is extremely difficult to identify a rough diamond as distinct from a synthetic one, as the two look very much alike. In fact, it is even harder than telling a genuine cut diamond from a fake. Call on our gemmology service in Angers or Paris, and we can help you obtain a certificate if you are in possession of a genuine diamond.
Useful to know, however: a genuine rough diamond is never perfectly symmetrical, unlike certain imitations. A real diamond will not normally float in water and will sink quickly, whereas fake diamonds tend to be lighter — though this is not always a reliable method.
Also worth reading: how to identify a ruby.
To identify a diamond ring, some people are lucky enough to find paperwork identifying the materials, most importantly the certificate of authenticity. Failing that, the way light disperses through the stone can sometimes resolve doubts, as it is truly characteristic of a genuine diamond.
The stone seems to shine from within, its light appearing to bounce across every facet, and depending on the lighting conditions, it takes on a different character altogether.
It is a magnificent, almost living phenomenon, and it is precisely what makes diamonds such exceptional stones. But to reliably identify a fine diamond on a ring — or unmounted — as opposed to a zirconium or any other stone, synthetic or natural, it is best not to rely on first impressions and to seek a professional appraisal instead.
Partagez ce post
Découvrez d'autres articles qui peuvent vous intéresser pour approfondir votre passion pour la joaillerie !
View all