"Gertler, Dan (DGI Group)". Rough and Polished: Information and Analytics on Diamond and Jewellery Markets. 3 December 2009. Archived from the original on 13 November 2011. Retrieved 15 November 2011.
"Gertler, Dan (DGI Group)". Rough and Polished: Information and Analytics on Diamond and Jewellery Markets. 3 December 2009. Archived from the original on 13 November 2011. Retrieved 15 November 2011.