Finally, the turquoise blue, variously named _fei ts’ui_ (kingfisher blue) and _k’ung ch’iao lü_ (peacock green), was freely used as a monochrome on figures and ornamental wares. It is a colour which descends from Ming times, and whose use has continued unchecked to the present day, so that it is often extremely difficult to give a precise date to any particular specimen, especially if the object happens to be of archaic form, a copy of an old bronze or the like. Its nature has already been discussed[337] among the Ming glazes, and one can only say that the K’ang Hsi pieces have all the virtues of the K’ang Hsi manufacture--fine material, good potting, shapely form, and beautiful quality of colour. The tint varies widely from the soft turquoise blue of kingfisher feathers to a deep turquoise green, and some of the most attractive specimens are mottled or spotted with patches of greenish black. The glaze is always minutely crackled, and has sufficient transparency to allow engraved or carved designs on the body to be visible. It is a colour which develops well on an earthen body, and the potters often mixed coarse clay with the ware which was intended to receive the turquoise glaze; but this, I think, was mainly practised after the K’ang Hsi period, and the K’ang Hsi specimens will, as a rule, be found to have a pure white porcelain basis. As in the Ming wares, the turquoise sometimes shares the field with an aubergine purple of violet tone, both colours being of the _demi-grand feu_. The purple is also used as a monochrome. There are, in fact, two aubergine purple monochromes, the one a thick and relatively opaque colour sometimes full of minute points as though it had been blown on like the powder blue, the other a thin transparent (and often iridescent) glaze of browner tone. Both are derived from cobaltiferous ore of manganese, both have descended from the Ming period, and have already been discussed as monochromes and as colours applied to the biscuit. [Illustration: PLATE 111 Two examples of Single-colour Porcelain in the Salting Collection (Victoria and Albert Museum) Fig. 1.--Bottle-shaped Vase of Porcelain with landscape design lightly engraved in relief under a turquoise blue glaze. Early eighteenth century. Height 8½ inches. Fig. 2.--Water Vessel for the Writing Table of the form known as _T’ai-po tsun_ after the poet Li T’ai-po. Porcelain with faintly engraved dragon medallions under a peach bloom glaze; the neck cut down and fitted with a metal collar. Mark in blue of the K’ang Hsi period (1662–1722) in six characters. Height 2¾ inches.]