"Coins made by DAECH, a so-called Islamic State," by Jérôme Jambu in Bulletin de la Société Française de Numismatique, December 2015.

Translated excerpts:

In conclusion the author notes that the dies, which are pictured in the article, were undoubtedly made by an experienced engraver, an arabisante because of the high quality of the workmanship and the carving of the legends which are similar in style to coins of the Arabian Peninsula. And concerning the metal required for fabrication the author notes that DAECH acquired a large quantity of gold ingots-approximately 200 kg-from the Banque Centrale Irakienne de Mossoul.

Chester adds:

To read the earlier E-Sylum article, see:
ARTICLES: AN INVESTIGATION OF ISIS COINAGE (www.coinbooks.org/esylum_v19n35a07.html)