Quick answer
What should I check before buying a diamond online?
Before buying a diamond online, check seven things: the exact grading report, natural or lab-grown origin, treatments, actual measurements/proportions, high-resolution imagery, total price against comparable stones, and the seller's written return/refund terms. For a fancy shape, add a visual check for outline, symmetry and issues such as bow tie.
Key takeaways
- Verify the report with the issuing lab.
- Confirm origin and treatment disclosures.
- Compare millimeter measurements and proportions, not just 4Cs.
- Inspect actual-stone media.
- Benchmark the price against like-for-like stones.
- Read return/refund and service terms.
- Save documentation before checkout.
1. Grading report
Confirm the report number, laboratory, measurements and grading data. For GIA reports, use Report Check or GIA's official report data rather than relying only on a seller PDF.
2. Origin and treatments
Confirm whether the stone is natural or laboratory-grown and whether treatments are disclosed. FTC guidance requires truthful representation of these material characteristics.
3. Measurements and proportions
Carat is weight, not visible size. Compare dimensions, depth and other relevant proportions so you do not pay for weight that is hidden rather than visible face-up.
4. Actual-stone imagery
Use video/photos of the actual diamond when possible. Check eye-cleanliness, transparency, symmetry, outline and light pattern. For oval/pear/marquise, inspect bow tie.
5. Comparable price
Compare the exact origin, shape, carat band, color, clarity, cut/proportions, grading lab and fluorescence/treatments. A broad average cannot tell you whether one stone is overpriced.
6. Seller terms
Get the return/refund policy in writing and check deadlines, exclusions, resizing, customization, restocking, shipping and warranty/service terms.
7. Preserve the evidence
Save the listing, grading report, invoice, seller representations and policy terms. If the delivered item differs from what was represented, documentation matters.
CaratSignal Research
Sources and methodology
- Buying Gemstones, Diamonds, and Pearls | Consumer AdviceFederal Trade Commission · Researched September 28, 2026
- Jewelry Guides | Federal Trade CommissionFederal Trade Commission · Researched September 28, 2026
- GIA Diamond Grading | GIA 4CsGemological Institute of America · Researched September 28, 2026
- Diamond Carat Weight | Understanding Carat Measurement | GIA 4CsGemological Institute of America · Researched September 28, 2026
CaratSignal separates laboratory grading facts, consumer-protection guidance and dated market-price observations. Market figures are snapshots of cited public listing datasets, not appraisals, guarantees of fair value or promises that a buyer will find a particular stone at that price.
Read the research methodology- First published
- September 28, 2026
- Last researched
- September 28, 2026
- Last updated
- September 28, 2026
- Research status
- published