Lab grown diamonds are 100% diamond! In fact, the Federal Trade Commission (FTC) has revised its definition of a 'diamond' to include both lab grown & mined diamonds.
In a detailed statement explaining the changes, the FTC notes, "The Commission no longer defines a "diamond" by using the term "natural" because it is no longer accurate to define diamonds as "natural" when it is now possible to create products that have essentially the same optical, physical, and chemical properties as mined diamonds."
Laboratory conditions for growing diamond result in the same natural growth process of a single crystal, 100% carbon structure that is created under the earth. The result is a stone that is likewise 100% diamond.
In the FTC amended Jewelry Guides, which are intended to help marketers understand their responsibilities with respect to avoiding consumer deception, the FTC also cautioned marketers not to use the terms “real, genuine, natural, or synthetic” to imply that a lab grown diamond "is not, in fact, an actual diamond.”