How to buy plain white mugs ? custom stoneware coffee mugs 2023

More Client do like to order white plain coffee mugs ,but most of clients don't know the stoneware (ceramic) white mugs and what's difference between the stoneware white and the super white porcelain?

stoneware (ceramic ) white mug :  the white have some a little yellow , the fired temperature at kiln is about 1250C 
the super white porcelain           :  with very shine white , the fired temperature at kiln is about 1300-1350C .

but the cost of porcelain materail price is higher than the stoneware of approx 20% . you  buy what's material white mugs depend on your market demand . 
Enclosed some photos ; 
with printing mugs is stoneware materail / some client called ceramic
without printing is super white porcelain .