Are lab-grown diamonds on Amazon real?
A lab-grown diamond is diamond: the same crystal of carbon as a mined one, with chemical and physical properties that, in GIA’s words, “correspond very closely to that of natural diamonds”. In 2018 the US Federal Trade Commission removed the word “natural” from its definition of diamond (16 CFR 23.12), so a lab-grown stone counts as diamond, provided the listing says laboratory-grown, or words of like meaning, right before the word. What a listing cannot prove on its own is the grade, or that the stone is diamond rather than moissanite, so buy one with an IGI or GIA report number and check it.
What lab-grown means
Lab diamonds are grown either by high pressure and high temperature (HPHT), in a press that recreates conditions deep in the earth, or by chemical vapour deposition (CVD), in which carbon from a hydrocarbon gas builds up on a , layer by layer, in a vacuum chamber (GIA). The result is diamond. Our guides to how lab gems are grown and CVD vs HPHT explain both methods.
What the listing must say
Under the FTC Jewelry Guides, the word diamond on a lab-grown stone must be immediately preceded, with equal conspicuousness, by “laboratory-grown”, “laboratory-created”, “[manufacturer name]-created” or words of like meaning (16 CFR 23.25), and sellers may not call it “real”, “genuine” or “natural” (16 CFR 23.27).
Lab diamond or moissanite?
Moissanite is a different, cheaper gem that some listings blur with diamond. A thermal diamond tester cannot separate them, because it reads moissanite as diamond (see does moissanite pass a diamond tester?). A 10x loupe can: moissanite is doubly refractive, so the back facet edges look doubled when you look in through a side facet; diamond never doubles. A laboratory report settles it.
Lab or mined?
You cannot tell by eye or with a home tester; GIA says that in some cases identification requires advanced scientific instruments. A laboratory report says whether the stone is laboratory-grown, and since 1 October 2025 GIA laser-inscribes “Laboratory-Grown” and its assessment number on the girdle of each lab-grown diamond it assesses. See can a jeweller tell if a diamond is lab-grown?
Frequently Asked Questions
Will a lab-grown diamond pass a diamond tester?
Yes. It is diamond, so it passes a thermal tester exactly as a mined diamond does.
Do lab diamonds get cloudy or change colour?
Not permanently. Some CVD-grown diamonds turn darker after strong ultraviolet light, such as the lamps used in gem testing, and return to their usual colour after more than 30 minutes under a daylight-equivalent lamp (GIA, Gems & Gemology, 2010). Diamond does not cloud; oil and dirt on the back of the stone are what make it look dull, and cleaning fixes it.
Sources
- GIA: HPHT and CVD diamond growth processes (properties correspond very closely to natural diamond; advanced instruments)
- US FTC Business Blog: “Diamonds and Pearls” and revisions to the Jewelry Guides (24 July 2018): “natural” removed from the definition of diamond
- US FTC Jewelry Guides, 16 CFR 23.12: definition of diamond, Cornell LII
- US FTC Jewelry Guides, 16 CFR 23.25: laboratory-grown stones must be qualified, Cornell LII
- US FTC Jewelry Guides, 16 CFR 23.27: misuse of “real”, “genuine” and “natural”, Cornell LII
- GIA: Updated laboratory-grown diamond services to launch October 1 (26 August 2025)
- GIA, Gems & Gemology: Color alterations in CVD synthetic diamond with heat and UV exposure (Khan et al., Spring 2010)
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