Note symbol on packages: This is what the black and white diamond means. DHL explains the meaning of the symbol with an information sheet.
Black and white diamonds on packages represent substances in “limited quantities” On many packages you can see a black andwhite diamond, which at first glance doesn't reveal what kind of notice it is. The minimum dimensions for the symbol must be 100 by 100 millimeters and the minimum width of the diamond boundary line must be two millimeters.