These are jiggered lids made from Plainsman M340 middle temperature stoneware. The one on the right was sponged in the dry stage to smooth issues that occurred during jiggering. That has exposed speck producing particles that were under the surface. This body is made from quarried materials that are ground to 42 mesh.
Specking is a fault in fired ceramic ware where speckles of ion bearing contaminants are visible and mar the appearance of the surface.
Every glossy ceramic glaze is actually a base transparent with added opacifiers and colorants. So understand how to make a good transparent, then build other glazes on it.