The Chinese developed a shell like, translucent porcelain for their glazed ceramics in the 2nd century AD. By the time of the Ming Dynasty (1368-1644), porcelain was being exported to Europe where it became highly coveted. Many attempts were made to reproduce porcelain in Europe, but none met with success until the eighteenth century, when the Chinese manufacturing secrets were finally smuggled into Europe. The famous Miessen factory opened in Saxony in 1710, producing pieces which fetched hugh prices - porcelain was very fashionable and 'everyone who was anyone' wanted some. But it was hard to produce.
Then came an important break through: bone china was developed by Josiah Spode in England in the late eighteenth century as a rival to porcelain. He devised the formula of roughly two parts bone ash to one part china clay and one part china clay which created this lovely white, translucent material. Not did bone china also have a lovely shell like sheen to it; it was also very strong. This meant that pieces could be made of very thin china, which increased their delicacy and translucence.
Cole of London's products are made of bone china. A lot of customers comment on the lovely thin lips of the mugs. Tea tastes better when drunk from a vessel with a thin lip. Bone china's strength makes these thin, translucent lips possible. So Cole of London thanks Josiah Spode for his ingenuity and his foresight in developing this wonderful material.