(IDEX Online) - Surat Diamond Bourse (SDB) is finally set to open by next April, after more than three years of delays.The $355m bourse (pictured) was originally supposed to open in January 2020, according to the SDB website. That was put back by September 2021, and then to 2022. Vallabhbhai Patel, chairman of the SDB project, said the government had now granted permission for the building to become operational, and Indian Prime Minister Narendra Modi would inaugurate the bourse.He insisted the building was complete, despite "negative" rumors to the contrary.SDB will be the world's largest office building, with nine 15-story towers covering a site larger than The Pentagon in the USA.It will challenge the dominance of Mumbai's Bharat Diamond Bourse currently the world's largest diamond bourse and home to around 2,500 traders.Surat has long been the capital of diamond manufacturing, handling over 90 per cent of all the world's gems, but the trade has been centered in Mumbai, a five-hour drive away.