Marketing Laws for Lab-Grown Diamonds: Why Terms Like “Synthetic” or “Real” Matter Legally

The core rule: you can market aggressively, but you can’t market misleadingly

In the U.S., the legal danger isn’t “selling lab-grown diamonds.” It’s using language that causes a reasonable buyer to assume something false—especially origin (mined vs lab-grown) and what the stone actually is (diamond vs simulant).

The FTC’s Jewelry Guides explicitly apply to gemstones and their laboratory-created and imitation substitutes, so lab-grown diamond advertising sits directly inside that guidance. 

The “diamond” word problem: what sellers can imply vs what they must disclose

Sellers can call a lab-grown diamond a “diamond” (it is one), but the marketing must not steer consumers into thinking it’s mined. The FTC’s business guidance on jewelry advertising is blunt: don’t use “laboratory-grown/laboratory-created/[name]-created/synthetic” unless the stone has essentially the same optical, physical, and chemical properties as a mined diamond—and the flip side is you shouldn’t be vague if the distinction is material. 

Miami buyer reality: in high-volume markets, some sellers rely on speed + social pressure. Your defense is getting the origin in writing on the invoice, not “the vibe seemed honest.”

Term-by-term: what “synthetic,” “real,” and “cultured” mean legally (or at least legally risky)

1) “Synthetic”

“Synthetic” is allowed for lab-grown diamonds in FTC guidance—but only when the product truly has essentially the same properties as a mined diamond (i.e., it’s actually a lab-grown diamond, not a simulant).

Where “synthetic” becomes a problem:

  • using it to confuse (“synthetic diamond” while hiding that it’s lab-grown)

  • using it to describe something that isn’t diamond (e.g., CZ) 

Buyer translation: “synthetic diamond” is not automatically sketchy. What’s sketchy is when the seller uses it to distract from disclosure or to blur the line with simulants.

2) “Cultured”

This is the word that causes the most nonsense.

FTC materials explicitly address using “cultured” to describe laboratory-created diamonds only if it’s qualified by a clear and conspicuous disclosure like “laboratory-created,” “laboratory-grown,” or “[manufacturer]-created.”

So “cultured diamond” by itself is a problem. It’s a word-game.

Miami buyer rule: if a tag, listing, or salesperson uses “cultured” without immediately saying “laboratory-grown/created,” assume you’re being managed.

3) “Real” (and “genuine”)

“Real” is not a technical grading term. It’s a persuasion word.

Using “real diamond” is legally dangerous when it’s used to imply “natural/mined diamond” while selling lab-grown. FTC guidance is fundamentally about avoiding deceptive implications in how products are described to consumers.

Practical takeaway: A lab-grown diamond can be a “real diamond” chemically. But if the context implies “mined,” you’ve crossed into the zone regulators care about.

The fastest way sellers create legal risk: burying disclosure

The FTC keeps coming back to one standard: clear, non-misleading description. The Jewelry Guides are meant to prevent deceptive claims in the jewelry industry, including for lab-created substitutes.

Common “bury the disclosure” tactics:

  • Big headline: “DIAMOND STUDS” / small print: “lab-created”

  • In-store: “Yes, it’s a diamond” (true) while never clearly stating lab-grown

  • “Eco diamond” / “conflict-free diamond” used as a smokescreen (and broad eco claims have their own FTC risk if unqualified)

Miami-localized: what to demand so you don’t get trapped later

You want language that survives:

  • insurance underwriting,

  • appraisals,

  • resale listings,

  • and disputes.

Minimum documentation checklist

  1. Invoice must say “laboratory-grown” (or equivalent) next to the word diamond.

  2. Lab report number you can verify on the grading lab’s database.

  3. If the seller uses “cultured” or “synthetic,” make sure it’s immediately paired with “laboratory-grown/created” disclosure (not hidden).

If they refuse any of the above, the issue isn’t “policy.” The issue is they want wiggle room.

Bottom line

In 2025, the safest marketing language is the most boring: “laboratory-grown diamond.” The spicier the wording (“real,” “cultured,” “eco”), the more you should demand hard proof and crystal-clear invoice language—because the FTC’s entire framework is built to punish deception-by-implication. 

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