Model and New York City–based yoga instructor Johan Montijano was the embodiment of ­business casual. The French-born athlete showed his ­laid-back side in springtime whites, his serious side in a sophisticated navy suit, and his playful side in a cozy brown sweater. Every look was complemented by a tasteful yet substantial assortment of jewelry, plus a statement-making timepiece. Now that’s the kind of model we’re talking about!   Faceted band in silver, $375, David Yurman, NYC, 212-752-4255, davidyurman.com; Nadav hammered ring in silver, $175, Zadeh New York, NYC, 212-744-2820, zadehny.com; bracelet in leather with a paraiba-blue topaz accent in a silver clasp, £235 ($355), Tateossian, River Vale, N.J., 201-966-7525, tateossian.com; Jannik chronograph watch in titanium and silicone, $245, Skagen, Reno, Nev., 877-752-4361, skagen.com; jacket: Zara Man; sweater: