170 East 77th Street (Diamond House)Recorded sales & closing prices

Individual unit deeds at Diamond House begin in 2007 and have been recorded in almost every year since, with 111 deeds across the residential lots through 2026. That is enough depth to build same-building comparables at most sizes, though not at every line — several apartments have traded only once since the conversion, and ten have never traded at all.

Pricing behaves like what the building is: a well-renovated prewar conversion on a quiet mid-block Lenox Hill street, without a garage, without a full amenity program, and without a marquee address. On a dollars-per-square-foot basis it sits below the Park and Fifth Avenue condominium tier and in line with the mid-block Lexington-to-Third condominium inventory of the East 70s. The larger three- and four-bedroom residences are the building's scarcest and strongest product, because floor plans of that size in a full-service prewar building on this corridor are genuinely limited in supply.

Two structural items should be priced into any analysis. The first is the standing 10 percent capital assessment, which raises the effective monthly cost above the headline common-charge figure. The second is the sponsor's remaining unsold inventory: a building in which a single owner still controls a meaningful minority of the apartments and rents them can face lender scrutiny on owner-occupancy ratios, and a buyer financing a purchase should confirm the current owner-occupancy percentage early rather than at commitment. Unit-level transaction history is maintained in The Roebling Research Library and shared with clients during diligence.