Personally, tortoise shell sunglasses can work well with a black-dominant or brown-dominant outfit. Just try outfit with a black-dominant or brown-dominant, and then put your tortoise shell sunglasses on to see if they can match each other. However, the most important one is that sunglasses should mainly match your complexion. If they can go well with your skin color, you can wear your tortoise shell sunglasses with any outfit.
It is depends on the color of the tortoise shell sunglasses and the gender and temperament you have. If you a men with a pair of black tortoise shell sunglasses, you can wear black business suit. If you a women, you can try a pair of black dress shirt and grey slacks. You can also wear black skirt. Again, if the your tortoise shell sunglasses are not black, you can wear some fat and unique T-shirt with jeans for a rock look.