Art history can come in small sizes, but with big price tags. Such is the case with portrait miniatures, where the wide range of subjects includes royalty, merchants and, eventually, well-to-do tradesmen, military heroes and statesmen. Prices are just as varied - from $800 to well over $100,000.

Some of the finest were done by well-known artists of the day on enamel. When the subject is royalty and the artist a documented and well-known miniaturist the price goes up. However, portraits of royalty are relatively common and, when the artist isn't recognized, the minis can be had for under $1,000.

Portrait miniatures were especially popular as love tokens when the portraits were of beautiful women. What makes them so fascinating to collectors are the historical details - from hairstyle to clothing and jewelry - and knowing the subject.

Credit German artist Hans Holbein is credited with development of the portrait miniature in the 16th century. He began using watercolors on vellum from 1532 to his death in 1543. These miniature portraits were called "limmings," which translates into "paintings on little."

British artist Nicholas Hilliard (1547-1619) is best known for his portraits of Queen Elizabeth I and was miniaturist to her court. However Christian Friedrich Zincke, born in Germany in 1683, came to England in 1706 and revived the art of enameling. He is considered by many to be the ultimate in this field.

Until the 18th century the portraits were painted with watercolors on vellum. Their true beauty was achieved in the early 1700s when watercolors were used on ivory. The finest results were achieved by the mid-18th century when the paintings were done over an enamel process. Hence the term "portrait miniature enamels."

In America, portrait miniatures became vogue by the mid-18th century and were created by famed artists such as John Copley and Charles Wilson Peale. The subjects weren't royalty but statesmen, military heroes, merchants and their wives. Copley's miniatures were done on copper, ivory and wood. Examples can be seen at Colonial Williamsburg and other museums. British examples are in the Victoria and Albert Museum.

The style of portrait miniatures changed in the early 19th century in England, America and Europe. Darker, more opaque colors were used. With the introduction of photography in the mid- to late-1800s, portrait miniatures went out of fashion.

CLUES: When portrait miniatures came to auction last year, prices were as low as $500 to several thousand dollars. However there are some perils and pitfalls when buying at antique shows, unless you know your dealer. Many are actually decals mounted on porcelain. A strong magnifying glass or jeweler's loupe is imperative. The faker will have taken the trouble to add hand-painted details that will be raised and lead the buyer to believe the entire portrait has been hand-painted. Another clue to those faked miniatures, usually from the Continent, is the aged and dated printed paper glued on the back of the enamel. Before paying too much, have the seller remove the back.

Carefully examine for condition. Facing, mold and water damage lower values no matter who the artist or the subject. Pass up ivory miniatures with signs of cracks. When stored in an uneven temperature ivory miniatures can split.