Egg rings are built to sustain high heat and can be dishwasher-safe if made of dishwasher-safe materials such as silicone and steel. Check the guidelines before using.
Sarah Blair, says, “I recommend washing the rings with warm soapy water and avoiding anything abrasive that might scratch or damage the rings. Hand washing is always better than a dishwasher for delicate items. Silicone can also retain the dishwashers soap and chemicals, which can unpleasantly permeate into your food.”