There is no unwritten rule about the size of the diamond in an engagement ring. You simply choose the ring that best suits your loved one, from fine and elegant to striking and imposing. Some choose for various small diamonds above a solitary example, because these cost less for the same carat weight. With a halo engagement ring, where a central diamond is encircled by various smaller stones, the diamond is made to look bigger. When the ring really must really stand out, the diamond can weigh up to 5 carats. However, most of the diamonds in engagement rings weigh between 1.00 and 1.09 carats.