Rustomjee Developers in Mumbai, owned by Keystone Group. The company is the manifestation of one man and thevision that he has. His name is Mr. Boman R. Irani. He founded Keystone Realtors Pvt. Ltd. In 1995, which started from the bottom, while exploring every aspect of the business and rapidly rising to be one among the topmost Builders & Developers in Mumbai.

The Rustom Irani Foundation was established in 1998 in the memory of Late Shri Rustom Irani, with the objective of "Making Education a Priority".

The Foundation established their first School 'The Rustomjee International School' - a premier English medium School in Mumbai, in 1999.

The group has achieved an enviable reputation within a short span of 5 years and has grown from 268 students in the first year to 4500 students in 2004.

Keystone Group started construction in Mumbai in 1996 and rapidly rose to be a premiere Construction Company due to its uncompromising commitment to the highest level of quality construction as well as its consistency in delivery schedules.Keystone Group has till date launched, completed and delivered, Residential complexes, premium homes and educational institutions.