Will a Sapphire Test as a Diamond?

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A diamond is definitely the most sought-after and one of the costliest gems on the planet. You would hardly find somebody who would be willing to exchange these extremely precious stones with any other gem discovered on the planet. Even the natural pearls and exquisite color-changing alexandrites stand faded when diamonds steal the spotlight.

The Vast World of Diamond Substitutes

The extreme rarity and skyrocketing prices of diamonds have made them the weakness of royalty rather than the strength of the working class. There are numerous other stones discovered throughout the world which resemble these vibrantly flawless crystals, like white zircon, cubic zirconia, white sapphire, white topaz, moissanite, etc. Though they are visibly distinguishable from diamonds, they are the closest alternatives to the heavily priced jewel available at comparatively affordable prices. So, for a layman, these popular substitutes might not be too different from real diamonds, but for a gemologist, it is just a matter of seconds to distinguish between all of them.

The Criteria for Diamond Testing

Diamond testing is the process by which thermal or electrical conductivity is measured in a stone to qualify it as a diamond. This test is conducted using a diamond tester which is a handheld pen-like device with a metal point on its tip. When it is touched against the surface of the stone, it is capable of measuring how swiftly the heat or electricity passes through the same. Apart from this, the hardness of the stone, its rainbow-colored reflection, and its refractive index are other criteria to test for real diamonds, for they are the hardest of all the gemstones that have been discovered to date, reflect all the seven colors, and display single refraction.

Diamond Testing


Which Stones do not Pass the Test?

Usually, one of the most anticipated diamond simulants, moissanite passes the diamond test in terms of possessing high levels of heat conductivity, but when it comes to the other criterion, its double refractive index differentiates it from the diamonds. Similarly, cubic zirconia, zircon, and white topaz are low conductors of heat and are not as hard as diamonds. So, each of the diamond simulants has one or more properties of diamond missing in them to qualify them as one.

Which Stones Would Pass the Diamond Tester?

So far, only the natural diamonds, the lab-grown diamonds, and the non-diamond moissanite have been able to pass the diamond test, mainly because it tests the stone only for its thermal conduction ability. However, the lab-created diamonds have exactly the same composition as their naturally mined counterparts, the only difference being, they are developed in labs rather than formed as a result of the mineral depositions under the earth’s surface. Though, repeated testing might be required in some cases due to differences in the level of heat conducted through the artificial ones and the differences in the techniques employed to form them.



Will a Sapphire Test as a Diamond?

The sapphires are usually deep blue colored crystals, but several other color varieties are already known to the world, one of which is the colorless or white sapphire stone. Though it looks very similar to the dazzling diamond, it would certainly fail the diamond test due to several reasons, the first being its low heat conduction capacity as compared to that of diamonds.

Besides, the sapphire gems lack the level of hardness diamonds possess, though the stone takes the 9th position on the Mohs Hardness scale, only one position down from the diamonds, which hold the 10th spot. It could be ascertained from the fact that the diamonds could scratch only when rubbed against other diamonds, while it’s not the case with the white sapphire since it could be worn off after being scratched by both moissanite and diamonds over time.


Sapphires also fail to reflect the rainbow colors, the most phenomenal visual treat offered by the diamonds. They rather produce silver and white sparkling effects, which become more prominent as the size of the stone increases. The bigger the stone, the easier it becomes to spot the difference in the physical properties of the two stones.

Another easy trick to separate sapphire gems from diamonds is to check if they turn red under a halogen lamp, if yes, then the stone is definitely a sapphire, and if not, then it’s undoubtedly a diamond. The gemologists also have additional tools to verify the authenticity of the diamond simulants, such as a loupe.

Final Thoughts

Though naturally extracted diamonds are rare, their optical, physical, and chemical compositions have long been utilized to create lab-cultured diamonds, and no other diamond simulant could take over this position. In case you have a thing for real sparkling diamonds, then save up a little before you look out for one; otherwise, you could always find a perfect substitute for them, GemsNY promises to assist you in this journey.

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