Triangle earrings. Geometric studs. This is an equilateral triangle. Equilateral(G) all sides are equal and each angle = 60°, making this the only equiangular triangle. Since all 3 angles are less than 90° all equilateral triangles are acute triangles.
It is the only geometric shape that gave name to an entire mathematical profession, Trigonometry demonstrating its importance......or we could just say that this is a lovely pair of post earrings!!!