Buttons date from at least 3,000 years ago, but buttons used as clothing fasteners date from circa A.D. 1200. The mass production of buttons began in the 18th century, and vintage buttons are largely those made in the 19th century and the first half of the 20th century. In particular, Victorian era (1837-1901) buttons are prized for their highly decorative nature. You can identify vintage buttons by their material, their mode of manufacture and their decoration.
Identify the button's material. Common materials of early buttons include metal (brass, pewter and silver-plated ferrous metals are most common), ceramic, glass, bone, shell, and thread or fabric. Around the turn of the 20th century, many buttons were made from composite, plastic-type materials such as celluloid and later Bakelite. Hard rubber such as gutta-percha became a popular button material in the early 20th century. The National Button Society provides a Beginners' Booklet with directions for identifying popular material types.
Identify the manufacturing process of the button. Certainly handmade buttons are vintage or antique. Vintage metal buttons were often made by stamping a piece of sheet metal with various designs and forming a disc around a mould with a separate shank or eye for attachment. Other metal buttons were cast in one- or two-piece moulds (particularly military and coat buttons). Ceramic and porcelain buttons can be moulded or handmade. Glass buttons were typically moulded, and buttons that were handblown by glassblowers are particularly collectable. Buttons made from composite materials like celluloid, Bakelite and gutta-percha were almost always mass-produced in moulds.
Identify the button's function or type. Collectors often make distinctions between military and civilian vintage buttons and those used for outer garments such as coats and inner garments such as trousers, shirts or underwear. Collectors also make a distinction between handmade and mass-produced buttons. Popular types of vintage buttons include silver-plated or brass Tombac buttons, porcelain Prosser buttons, handblown glass buttons and highly decorative celluloid and Bakelite buttons. Military buttons are particularly popular among collectors. Vintage military buttons are almost always metal and made from brass, pewter and silver-plated ferrous metal.
Research manufacturers' marks. Many vintage buttons have manufacturers' marks and other information stamped or printed on the reverse side of the button. Researching a button's manufacturer will help date the button and provide more information about how it was made. Guides to button-back marks are particularly useful.
According to the BBC, the most popular button of the 19th century was the black glass button worn as a morning button after the death of Prince Albert.
It can be very difficult to tell the difference between a porcelain button and a glass button, especially when they are white. You may need to consult a professional antiques appraiser.