An diptych of the Passion of Christ, crafted between 1360-1380, fetched 4 million euros ($6.6 million) in Paris on Monday - a world record for a medieval ivory art work, Sotheby's auction house says.The work is also the largest diptych of the Passion ever registered, stretching to 31.4 centimetres when opened.It was part of a stunning medieval French collection of ivory and champleve enamels in excellent condition, known as the Dormeuil Collection, which fetched a total of 9.45 million euros. Other pieces included a small ivory statue of Virgin Mary and infant Christ, dated around 1250. It sold for 1.5 million euros.One of the jewels of the collection, a champleve enamel reliquary of Saint Thomas Becket, fetched 570,000 euros.