The Classic Miniature has a long and venerable tradition, perhaps back to the Ancient Greeks, but certainly to the Medieval Illuminated Manuscripts.  The tradition is then traced through the Portrait Miniature of Elizabethan times, painted in Watercolour on Ivory for brooches & lockets.  Miniatures were given new life during the Victorian times, and in the 20th century the present day Miniature Societies were born.  The Classic Miniature is not merely a small painting (though many small works are wrongly called Miniatures), but is a small work built up with layers of transparent & translucent colour, and usually in detail, no matter the Medium, whether Watercolour, Oil, Gouache, etc.  Using these methods a little jewel of a painting is the striven for result.