Doxa Watch SUB 300 Beta Ceramic Steel Aqamarine Rubber Black 830.10.241.20. Stainless steel case, ceramic bezel, sunburst-finish dial with a wave pattern: tool-watch engineering meets urban elegance. The perfect blend of a technical, robust and reliable watch with urban elegance. The diving watch that is equally at ease on a reef, in a boardroom, and any situation in-between. The 'β' for ‘BETA’ factor from DOXA: a palette of colors and fresh finishes paired with a subtle bezel redesign for sleekness.