Graff Diamonds is seeking court orders mandating the return of two allegedly stolen diamonds that subsequently turned up at the Gemological Institute of America’s famed grading lab.

The stones in question—one, a 16.4 ct. yellow, the other, a 4.2 ct. stone of unspecified color—were allegedly nabbed from Graff’s London store as part of a 2007 $20 million armed robbery, according to legal papers filed in the Supreme Court of the State of New York.

In a complaint filed Jan. 6, Graff’s attorney charges that, following the robbery, Hong Kong-based Yau On Company—also known as Yau On Pawn Shop—submitted a 16.28 ct. modified cushion cut to GIA. “Analysis performed by GIA revealed that the stone submitted to Yao to the GIA was the [16.4 ct. yellow] diamond,” said the complaint.

The diamond is now being held at the GIA, the suit says, pending resolution of the dispute. Graff is demanding that GIA and Yau On give it the diamond, as the company is the gem’s “rightful owner.”

Yau On could not be reached for comment by JCK, but a spokesman reportedly told the Associated Press that he paid three million Hong Kong dollars for the stone and had no way of knowing it was stolen.

A separate suit charges that Gabriel Jana submitted a diamond to GIA that, according to lab analysis, was the 4.2 ct. stone stolen in 2007. GIA is also keeping this diamond in its lab, but court papers say, won’t return the diamond to Graff without a court order. The court papers charge the diamond was purchased for less than “fair market value.”

GIA and Graff’s attorney both declined comment, citing pending litigation. The lawyer said to be representing Jana also did not return a phone call.

JCK