A gravity valve is adapted to control the flow of a downhole fluid through the downhole tool. The gravity valve typically includes a plunger and a seat. The plunger embodies a substantially non-spherical end that is adapted to mate with a complementary receiving end on the seat. The increase surface area of contact between the plunger and the seat acts to improve the seal to reduce the stresses thereon, and improve the performance of the gravity valve in general. The components of the gravity valve are constructed of materials, which are selected based on the specific gravity of the materials in comparison with the specific gravity of the downhole fluid for a given application.