Agate - Oxford Definition

A fine-grained, banded chalcedony which can come in all colours in a variety of strengths. It is often an opaque grey which can be sliced and polished to bring out the concentric patterns. It can also be dyed to strengthen the colour, an art known to the Romans. By the 16th century the most important deposits were in the Rhineland and a local industry sprang up at Idar-Oberstein, creating gemstones from locally mined agate. In the mid-19th century there were 153 polishing shops in the area and agate had to be imported from Brazil. Agate was used for a wide variety of decorative objects. The Egyptians used it for cylinder seals, ring stones, and small vessels. Later it was employed as a layer stone from which cameos were cut and mounted into jewellery, as well as other small items such as handles for knives and forks, manicure sets, and pill boxes. The main sources of good agate today are in Brazil and Uruguay.