Blue Nile, which for years resisted selling lab-grown diamond engagement rings, is now offering them side-by-side with natural diamonds on its site.

Blue Nile has long sold lab-grown diamonds produced by De Beers’ Lightbox brand, but has, until now, not sold them for engagement rings.

The e-tailer was acquired by Signet in August.

Blue Nile’s inventory appears to be a little different than some of its competitors’. It seems to offering a large number of D-color diamonds, likely because they were produced with the high-pressure high-temperature (HPHT) method, which is considered better at producing high-color diamonds than the chemical vapor deposition (CVD) method. Most HPHT diamonds are grown in China.

While Blue Nile executives once said the site’s average sale was around $10,000, its lab-grown diamond selection includes many stones in the $1,000–$2,000 price range.

Blue Nile also appears to be selling them primarily with GIA reports, in keeping with its longstanding practice. Though GIA has been grading lab-grown diamonds since 2020, the leading lab for natural diamonds has not been widely embraced among lab-grown diamond companies.

It’s also not clear if lab-grown diamonds are subject to Blue Nile’s trade-in policy, which, it says, covers “All GIA or [AGS Lab-]graded natural and colorless diamonds purchased from Blue Nile.”

But it also says: “Upgrades are available on a like-for-like basis (e.g. lab grown for lab grown or natural for natural). Upgrading from natural to lab grown or vice-versa may be eligible on a case-by-case basis.”

Blue Nile’s trade-in policy “is being reviewed as well as part of integration and will likely be similar to James Allen’s,” a Signet spokesperson tells JCK.

James Allen’s trade-in policy covers both lab-grown and natural diamonds and can be seen here.

At press time, the site called its lab-grown diamonds a “sustainable option.”

The spokesperson says “we’ve asked the Blue Nile integration team that is reviewing their advertising to remove” the “sustainable option” comment.

In 2019, the Federal Trade Commission cautioned lab-grown sellers not to make “unqualified general environmental benefit claims”—specifically singling out use of the word sustainable—warning that “it is highly unlikely that they can substantiate all reasonable interpretations of these claims.”