The cyclotron was the first of the irradiation methods to emerge in the early 1940s. In a cyclotron, ionized particles are accelerated to a high energy level by means of a high alternating voltage while circulating around in a strong magnetic field. After the particles reach a high enough velocity, they are channeled through a small opening as a particle beam, which in turn, bombards the diamond. The resulting colors are commonly greenish or yellow to orangish-brown hues, depending on the amount of annealing (heating) after the bombardment. This method is usually easy for the analysis labs to detect as it leaves obvious clues. The diamond in question is immersed in methylene iodide. Under microscope magnification, depending on which side of the diamond was exposed to the particle beam, a concentration of color is detected around the crown or the pavilion. Sometimes both the crown and the pavilion is exposed to the particle beam, in an attempt to obtain a more even color distribution.