The art of pottery is one of the earliest human practices, and few other cultures have demonstrated more innovation, craftsmanship and design in this art form than the Chinese. Although porcelain - or china, as it is commonly called in English-speaking countries - was first produced some 2,000 years ago, bone china wasn't invented until the 18th century in London, England. Bone china contains 30-45 percent bone ash derived from the bones of animals, which creates a warm white color and translucent finish. This type of porcelain is coveted for its durability and strength, enabling it to be used for thinner pieces. Bone china has been produced by some of the most prominent British porcelain manufacturers for many years, including Royal Crown Derby, Wedgwood and Royal Doulton. Many early examples of bone china were unmarked, meaning that there is often difficulty in identifying genuine pieces from this period.