Real turquoise is distinguished from imitation by weight, temperature, and hardness — natural stone is dense, cool to the touch, and resists scratching, while dyed howlite or plastic feels light and warm. The most reliable proof, however, is a seller who discloses the stone's mine, treatment, and maker in writing.
No home test is conclusive on its own, so begin with the most reliable signal: disclosure. A reputable seller states plainly whether a stone is natural, stabilized, or an imitation, names its mine where that is known, and backs the claim with a Certificate of Authenticity. Where that documentation exists you rarely need to guess; where it is missing, treat the piece with caution no matter how convincing it looks.
The physical cues are useful as supporting evidence. Genuine turquoise is a stone, so it has real heft and stays cool to the touch for a moment when you pick it up, while plastic and resin imitations feel light and warm almost immediately. Turquoise also sits at roughly 5 to 6 on the Mohs hardness scale — harder than a fingernail but softer than quartz — so it resists the casual scratching that would mark a soft substitute.
Know the common imitations. Dyed howlite and dyed magnesite are the most frequent stand-ins: both are naturally white stones with dark veining that take blue dye convincingly, but the color is only skin-deep and can rub off or pool in the drill holes. "Block," or reconstituted turquoise, is ground turquoise dust bound with resin into a uniform material. Plastic, ceramic, and even dyed chalk are also sold as turquoise to unwary buyers.
Be careful not to mistake treatment for fakery. Stabilized turquoise is real turquoise — softer natural stone infused with clear resin to harden it for cutting and wear — and it is a legitimate, widely sold material; most turquoise on the market is stabilized to some degree. The distinction that matters is honesty: natural untreated stone is rarer and more valuable, so the treatment should be disclosed and the price should reflect it.
A few field tests circulate — touching a hot needle to the stone to smell for plastic, or rubbing with acetone to lift dye — but they risk damaging the piece and are easy to misread. They are no substitute for provenance. The only real certainty comes from a documented chain: a named mine or origin, a stated treatment, a named maker, and a written guarantee.
In short, use the physical cues to raise or lower your suspicion, but buy on documentation. A genuine, artist-made turquoise piece from a seller who discloses mine, treatment, and maker is verifiable in a way that no fingernail or needle test can match.