From top: Stephen Russell’s platinum, 18k gold, fire opal and diamond necklace, $85,000, at Stephen Russell, New York, 212.570.6900; Bertolucci’s 18k rose gold, mother-of-pearl and diamond watch with satin band, $15,500, 212.204.0580,; Neil Lane for De Beers’s platinum and diamond necklace, $180,000, at De Beers, New York, 800.929.0889.

Warm weather and seaside retreats evoke a breezy attitude, often with ensembles to match. But embracing an easy aesthetic is no reason to forgo the finery entirely. In fact, it’s an opportunity to accessorize with high-end bohemian flair. Consider Neil Lane’s green and brown rough diamond necklace for De Beers and Stephen Russell’s fire opal and diamond chain. Both work colorful, offbeat gems in mismatched shapes and sizes to laid-back, slightly earthy effect. Elsewhere, things are overtly marine-inspired: Bertolucci’s sea urchin–shaped rose gold watch, set with diamonds and a mother-of-pearl face, is quite a catch.