Refers to necklaces and more forms. The form is handmade of clay /white, red or another colour/ or  from plastic porcelain mixture.
To some mixtures is added finely ground black enamel. Others are colored with additional metal oxides /chrome,  cobalt, manganese, copper, etc. - these are some of the most common oxides in ceramics/.
Colorants are included both in the angoba /liquid clay/ and in the glaze. The firing is usually done twice, and when there is a glaze coverage, a third time firing is needed. In various materials /and they are many/ temperature varies between 1080 - 1250 degrees Celsius.