An improved x‐ray collimation system for diamond‐anvil high‐pressure cells is described. The usual practice of mounting the collimator directly in the diamond‐anvil cell is not followed. Instead, the collimator is mounted and aligned in a fixture which can be removed from the diamong‐anvil cell. The end of the collimator furthest from the sample can be fitted with a set of removable plugs, each with a different aperture. This collimation system is easily aligned, can be removed from the high‐pressure cell with no loss of alignment, and is inexpensive to construct.