Predicting the future is always a tricky business.

Predicting the future is always a tricky business.

But most designers—whether they work in fashion, fabrics, architecture or even, say, jewelry—make it their business, literally, to divine what consumers will want next. Can kid mohair become the new cashmere? Will tanzanite ever replace diamonds? Can consumer conscientiousness co-exist with the new luxury? Designers put forth these questions first, and then they find the technology or the raw materials or the audacity to propose them as ideas. As Miuccia Prada points out, often the idea that seems the least likely to succeed is the one that becomes the best seller. Today technology moves quickly, and tastes are changing accordingly, but...