The tenant, a leading provider of natural stone to architects and designers, will add the 5,087 square feet in 2013. The expansion means Stone Source will occupy the entire seventh floor. It leased 1,296 square feet of expansion space at 215 Park South in January 2008.

Cushman & Wakefield's Mitchell Arkin and Mark Mandel represented Stone Source in the transaction, while Howard J. Tenenbaum and Gary M. Rosen acted on behalf of SL Green. C&W also represented Stone Source in its March 2007 lease of 89,000 square feet at Rreef's Meadowlands Distribution Center in Carlstadt, NJ, where the tenant has its New Jersey showroom.

The 330,000-square-foot 215 Park South was built in 1914 and is currently about 96% occupied. Asking rent there is $55 per square foot, according to SL Green's website. Other tenants at the property include Houghlin Mifflin Co., H&M, Kimball International and Perkins and Will.