An elegant, casual, dressy, and simple look for this Spring/Summer is shown below. The jacket appears to be black, yet a navy blue jacket can be another possibility for this outfit. The shades are Tortoise Wayfarers; if the jacket is black I'd wear Black Wayfarers, the Tortoise ones are better with a navy jacket imo. Wayfarers are probably my favorite shades ever since many years (way before their 2007 boom), but for this outfit I also recommend wearing aviators, Persol Rattis, or big 70s inspired shades (which are making a comeback this year).
What makes this outfit casual, young, and fun at the same time is the white tank top. A nice option to wear for a lunch this summer, to stroll around the city in the afternoon, and to party with your friends at a club, bar, or house (without the shades!).