Abstract: The invention relates to an unsaturated polyester resin comprising fumaric acid and optional end-capping with an ethylenically unsaturated moiety, which is useful for the preparation of engineered stone. The unsaturated polyester resin can be further processed to obtain a formable composition which can be cured to finally yield engineered stone as composite material. The thus obtained engineered stone shows a high resistance to UV- and sunlight as well as to weathering. The invention also relates to a method for the preparation of engineered stone as well as to the use of the unsaturated polyester resin for the preparation of engineered stone.