The brooch has not really changed much over the centuries. Basically, it is an ornamental piece with a pin of some sort. Its purpose has changed, however, as originally brooches were used to hold a tunic together at the neck or to keep a veil around the throat. It slowly moved from having a practical use to a predominantly ornamental use over time. The clasps, hinges and other findings used for brooches can assist date them. The first type of brooch was the fibula which had a straight pin which was threaded through the garment and then caught up behind a part of the brooch. Then the pin was bent and coiled into a circle, becoming the forerunner of a safety pin.
The next main developments in brooches were the Celtic penannular brooch, a crescent shaped brooch, the circular brooch, basically a round brooch which originated from simple discs of coiled wire, and the ring brooch, which was popular in the 13th century. None of these had a clasp.
It was not until the 14th century that clasps began to be used on brooches. They took the form of a C and C-clasps would continue to be used up until the early Edwardian period.

Some of the Georgian and early Victorian brooches had clasps that extended beyond the edge of the brooch.

The pins were attached to the brooches using tube hinges.

In the mid 1850s, the European trombone catch also began to be used.

Next week, I will talk more about brooch clasps and hinges.