Meet Instagram’s new power sellers, style influencers who are changing the face of modern marketing A recent Instagram post from jewelry retailer Bernie Robbins Jewelers showed a young blond woman standing in front of the colorful, whipped meringue–shape domes of St. Basil’s Cathedral in Moscow’s Red Square. The woman’s eyes were closed peacefully to the setting sun, her left arm flung over a shoulder. Gleaming on her wrist was a chunky steel watch. Jewelry brand Gabriel & Co.’s Instagram account (@gabrielandco) was tagged, and the hashtags included #BernieRobbinsJewelers and #BernieRobbins. The woman was Kristina Smolyar, a social media ­influencer with 14,000-plus followers, who’s based in Philadelphia—near two of the Somers Point, N.J., retailer’s four locations. The Instagram post—along with several others on both Smolyar’s and Robbins’ feeds—was th