Global fashion brands from luxury to high street have woken up to the Islamic calendar. Around the muslim fashion world, brands run fashion promotions for Ramadan and Eid -- the "new Christmas." In London, luxury retailers gear up for the "Harrods Hajj," a seasonal pre-Ramadan influx of affluent Gulf shoppers.

Sometimes, fashion brands create a capsule collection from their existing ranges (DKNY led with a Ramadan campaign in their Gulf stores in 2014, for instance). And a specialist fashion-industry infrastructure has also grown globally -- now Muslim designers of modest wear have opportunities to show their work at the proliferating number of modest fashion weeks and fairs around the world.

In the mainstream luxury sector, online portal Net-a-Porter forged ahead with an Eid edit in 2015. Last year, new Dubai-based modest e-retailer The Modist showed sufficient confidence in a Muslim market to persuade high-end designers, such as London-based Mary Katrantzou, to produce exclusive modest designs.