Yes, a blue sapphire engagement ring can be suitable for regular wear, depending on the quality of the stone and the setting of the ring. Sapphire is a durable gemstone that has a hardness of 9 on the Mohs scale, making it one of the hardest gemstones after diamond. However, it's important to note that sapphire rings can still be subject to damage or scratches if they are not cared for properly. When purchasing a sapphire ring for regular wear, it's important to choose a setting that will protect the stone and keep it secure. A bezel setting, for example, is a good option as it encircles the stone with metal and provides a protective barrier. Additionally, it's important to clean and maintain the ring regularly to keep it looking its best.