AE (Æ)AE is a symbol for bronze and other copper alloys. AE is often used with a number indicating the coins size either in millimeters or using the following scale: AE2 = 21mm – 25mm AE3 = 17mm – 21mm AE4 = less than 17mm | AE (Æ)AE is a symbol for bronze and other copper alloys. AE is often used with a number indicating the coins size either in millimeters or using the following scale: AE2 = 21mm – 25mm AE3 = 17mm – 21mm AE4 = less than 17mm |