Ningbo Textiles

The plates have no designs on them, cept for something that’s sort of ridged around the rim area, but it’s just an imprint, and isn’t colored. The entire plates are white. On the bottoms of them it says “Gibson” – “China”. Could these have lead in them, or does that only apply to the ones that are colored and painted? If they might or probably do contain lead, can someone link me to a kit I can purchase, with which to test them?