1. Snuff-bottles imitating a natural stone, as amianthus, malachite, or chalcedony, formed by the simple _interpenetration_ of masses of glass of different colours. Such bottles are generally not carved on the surface. 2. Those of the nature of an onyx, built up by the _superposition_ of two or more layers of glass of different colours, the under surface being exposed in places by the carving away of the upper layers as in a cameo. We thus get a carnelian red or a deep blue design on a milky white ground. In other cases a jade-green passes by gradation through a pink layer to a pure white. Such an arrangement may be skilfully made use of to obtain a blend of colours on the petals of a lotus or other flower. 3. In this class the superficial colours do not enclose the whole core, but lie scattered on the surface. By this means green, red, blue, and yellow patches, all standing on the same level, may be made use of in the design. In such work we may see the climax of the Chinese technique in this _genre_, and the result has apparently been brought about by placing these patches of coloured paste on the sides of the mould before the introduction of the core of plain glass. Though this is technically a triumph of ingenuity, the flasks thus decorated are by no means the most beautiful of the series. Besides these, many other methods of decoration may at times be found on these snuff-bottles; we see elaborate designs painted in enamel on the interior, showing through the transparent glass, or again an opaque paste resembling porcelain may be decorated with colours on the surface. Avanturine glass is probably of late introduction, but spangles (of reduced copper) are sometimes made to appear locally in the clear glass as a golden cloud.[279]