Some facts on this product that plates, cups, mugs, tea sets et. are made of :
1) The base material for this product is clay and bone ash,
2) The bone ash is what provides the "calcium",
3) When this mix of clay mixed with calcium (and other components that make the "body") it is ready for firing,
4) Firing the wares make it hard, white and translucent,
5) Firing the wares to the correct high temperature make the wares vitreous (does not absorb water and therefore does not crack due to water absorption) , extremely hard and brings out the shine/translucency in the product,
6) After this, decals (stickers that bond permanently with the plates) are fixed by firing the wares again.
Apparently, in England they parked a double Decker bus over 4/6 cups of bone china and it did not crumble ... shows the strength of good quality bone china.
While storing plates for a long time please ensure that the plates are kept vertical or that every plate is separated from the other with some tissue paper or cloth napkin. This prevents crazing.
CAUTION: Apparently, 35% of the cost of production in a bone china plant is the cost of fuel (electricity/oil/gas) and several cheaper products cut corners in this process to be "cost effective". A simlple way to test the strength of the wares is to tap the edge with a metal piece (a spoon will do just fine) and listen to the sound it makes. Its best to compare to products at the same time - the higher the tone of the sound it makes - the better the product (same process works well with crystal glass) .