Tony Tseng established Diamond Windows & Door Manufacturing in 1992. Tseng followed his father s footsteps into the building and construction trade as a contractor. He entered into the window manufacturing business with a understanding of the product quality required to meet and then exceed the expectations of architects, specifiers, contractors and end-users. The company has developed one of the most comprehensive vinyl window offerings on the market with high-performance Low E and Heat Mirror glass and custom-designed products featuring exclusive DuraSeal insulated glass that has warmer inside glass temperature and lower condensation than ordinary glass. Its aluminum window products are available with a range of glass, screen, limit lock and muntin choices. Most products can be curved to meet field conditions. In addition, most aluminum surfaces can be coated with a variety of finishes, such as paint conforming and anodize conforming. Diamond Windows & Door Manufacturing is located in Dorchester, Mass.