Lucy's Diamond Insights
Deep market analysis, price trends, and diamond buying intelligence from Lucy, our resident diamond market analyst.
Subscribe via RSSDecode HRD and AGS Certificate Numbers, the Less Common Labs
HRD and AGS certificate numbers follow patterns that most diamond buyers never learn, until a confusing listing forces the issue. Our decoder handles both labs, including the tricky cases where an eight digit number could be an HRD cert or a retailer SKU.
Decode an IGI Certificate Number, the Lab-Grown Specific Guide
IGI grades more lab-grown diamonds than any other lab, but inconsistent report number formatting and high production volume make cert decoding trickier than you'd expect. We walk through the nine digit format, the disappearing LG prefix, and a worked example narrowing a 2ct E VVS2 oval to a single match.
GIA does not grade cut on fancy shapes: what 2.8 million reports reveal about the industry's invisible convention
GIA assigns an overall cut grade to one shape only.
Decode a GIA Certificate Number From Specifications Alone
Every GIA graded diamond has a unique ten digit certificate number, and you can reverse engineer it from the specs alone. This guide walks through the exact narrowing process, from shape and carat down to measurements, using a real worked example.
The fluorescence discount is not flat: how 395,554 GIA listings show the price hit running from -23 percent on D to zero on H Medium
Conventional buying advice treats fluorescence as a single-direction penalty: avoid Medium and Strong fluorescence to dodge a price discount.
How to Find a Diamond Certificate Number When the Retailer Has Hidden It
Retailers who hide the certificate number are betting you won't do the research. Our 16 million diamond database can identify almost any stone from its grading specs alone, turning a redacted listing into a fully traceable diamond.
The lab-natural price gap is not 70 percent: what 1.5 million listings reveal about how the spread widens with carat
Industry shorthand says lab-grown diamonds are 70% to 80% cheaper than natural at matched specs.
IGI vs GIA grading on lab-grown diamonds: what 67,000 oval cohorts reveal
Across 66,477 lab-grown D VVS2 ovals graded by IGI or GIA and tracked at active retailers in the Carat Hunter index, the IGI median price is $1,206 and the GIA median price is $1,978.
GIA's Premium-Standard pivot: what 335,669 lab-grown stones reveal about the new tier system
GIA shifted lab-grown diamond reports from the traditional D-Z color and FL-I3 clarity scales to a binary Premium-Standard tier system effective October 1, 2025.
Cross-retailer diamond pricing: what 4.7 million matched listings reveal
Across 4,704,553 certified diamonds tracked at two or more retailers in the Carat Hunter index, the average price spread is $1,592 per stone.