What is a diamond? The FTC definition
The words the FTC Jewelry Guides use, and what they mean for a listing.
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The definition
Section 23.12 of the FTC Jewelry Guides says: "A diamond is a mineral consisting essentially of pure carbon crystallized in the isometric system." The Guides give its hardness as 10, its specific gravity as approximately 3.52, and its refractive index as 2.42.
Seventeen polished facets
Under section 23.12(b), the word "diamond" on its own should describe a stone that meets the definition and has been symmetrically fashioned with at least seventeen polished facets.
Rough diamonds
Section 23.12(c) says "rough diamond" may describe uncut or unfaceted stones that meet the definition.
Stones with fewer facets
The Guides allow the word "diamond" for a stone with fewer than seventeen facets when the listing gives the number of facets and the shape, or names a shape type such as "rose diamond".
Mined and laboratory-grown
In its 2018 notice, the FTC said the revised Guides "eliminate the word "natural" from the definition of diamond" because "lab-created products that have essentially the same optical, physical, and chemical properties as mined diamonds are also diamonds." So a laboratory-grown diamond is a diamond. The Guides say how a seller should name it; our laboratory-grown diamond guide has the details.
Industrial grade stones
A note to section 23.12(b) says it is deceptive to represent industrial grade or other non-jewelry quality diamonds as jewelry quality.
FAQ
General information only. We are not a jeweler, appraiser, or gemological lab, and we do not grade, appraise, or verify any stone or metal. Before you buy, read the seller's full description, including whether a diamond is mined or laboratory-grown, any treatment, the metal's karat or fineness, and the weight, and check any grading report with the lab that issued it.
Next: carat weight
Carats, points, and fractions.
