The first miniaturists used watercolour to paint on stretched vellum, or (especially in England) on playing cards trimmed to the shape required. During the second half of the 17th century, vitreous enamel painted on copper became increasingly popular, especially in France. In the 18th century, miniatures were painted with watercolour on ivory, which had now become relatively cheap. As small in size as 40 mm × 30 mm, portrait miniatures were often fitted into lockets, inside watch-covers or pieces of jewellery so that they could be carried on the person. Others were framed with stands or hung on a wall, or fitted into snuff box covers.