The Fred F. French Building (Photo: Curbed)

The International Gemological Institute has signed a 10-year, 20,400-square-foot lease at 551 Fifth Avenue in the Diamond District—the Art Deco tower known as the Fred F. French Building.

IGI’s president and chief executive, Jerry Ehrenwald, estimates that the new space offers about 15 percent to 20 percent more usable space than the institute’s current location at 589 Fifth Avenue. The building’s owner, The Feil Organization, will be making alterations to the seventh floor to accommodate the new tenants.

“We will get much more usable space out of the new floor that we’re renting because they’re building it to suit,” Mr. Ehrenwald said.

The institute, which houses a school for gemological studies and certification, will expand its educational facilities. “The school will be enlarged so we have more classroom area,” Mr. Ehrenwald said.

More classroom space is required as the institute has seen an increase in demand for gem appraisal certification, he explained.

Mr. Ehrenwald would not disclose the per-square-foot asking price, but a spokesperson for IGI said the new space is under construction and will be ready for occupancy by February 1.

Jarod Stern of Studley represented IGI in the deal. Neither he nor a Feil spokesperson could be reached for comment.

Other tenants at 551 Fifth Avenue include the female-owned law firm, Schoeman, Updike & Kaufman LLP, which leased a little more than 16,000 square feet on the 12th floor in a deal announced this past September.

Last August, retailer Tommy Bahama unveiled plans to open its first standalone New York store in the building this month, having signed a 12-year lease for 8,500 square feet there in January of 2011.