Terry Castro, a New York-based jewelry designer whose knack for blending the fantastical with the elegant propelled him from selling on the sidewalks of New York to adorning celebrities like Rihanna and Steven Tyler, died on July 18 at his home in Istanbul. He was 50.

The cause was a heart attack, his son, Sir King Castro, said.

Mr. Castro, who worked under the single name Castro, considered himself a “creator of dreams.” He scoured antique shops and thrift stores for inspiration for his cheeky yet sumptuous pieces, which mixed animal and human forms and invoked African influences with medieval and galactic imagery. He produced only about 35 pieces a year, by hand, but he saw his work featured on the covers of Vogue Latin America, Forbes and Hamptons magazines, and in the 2013 feature film