Prince Charles souvenir ceramic mug. Tested positive for lead at 300 ppm. No mark or maker noted. Tested with an XRF instrument in 2013.
The amount of lead that is considered toxic in a modern/newly manufactured item intended for children is anything 90 ppm lead or higher. Mugs are not considered items intended for use by children and, as such, are not regulated for total lead content as detectable when tested with an XRF instrument.