If you can see a lot of light coming through the piece, you most likely have china with bone ash in it. Examine the color. Noritake also notes that the color of bone china tends to be more ivory than white. If your piece is pure white, it is more likely to be hard or soft porcelain.
Is it safe to use vintage china?
Leaching lead from antique china may be toxic. And those pieces of china with decorations atop the glaze rather than beneath the glaze may contain lead. If any of your pieces of antique or vintage china or pottery is damaged in any way (chips, cracks, crazing, etc.), dont use it in the preparation or service of food.