When Katherine Jetter’s opal distributors told her that cutting into opals was considered verboten, she didn’t abandon her plan to create blossoms with the iridescent gems. “I really fought with my mining guys,” she says. “The old-school view is to not cut down opals, which is why opals are so often these ugly, weird shapes.” The blue-green stones composing the petals in this piece—dubbed Miss Minty for its mint-green tourmaline center—required months to source; it can take “up to six months to find four matching stones that have enough size and dimension to withstand the cut,” explains the designer, whose native Australia is home to the Daintree Rainforest that inspired her Exotic Flowers series. “The rain forest is deep and dense,” she says, “so I wanted to create a sexy, magical flower that had some danger to it.”Bold StonesThe incandescent ring features an