Porcelain has been in use for over 4000 years in China. It is made from special white clay and fired at a temperature of 1280 degrees centigrade. There are a couple different ways in which these items are decorated. The most common today is molded, decorated, and glazed. Others are molded and enameled then fired again. The third type is under glaze in blue and red. The Chinese have always been extremely proficient at porcelain work, and have produced numerous pieces that look like coral, glass, stone, and many other materials. 

Chinese Porcelain by David Pullens 

Since the Chinese did not produce large numbers of snuff bottles of porcelain until about 1800 (during the Jiajing period) any porcelain snuff bottle claiming to be before this date should be looked upon with suspect. And as a general rule, the porcelain quality (porcelain and not necessarily decoration) of Chinese pieces has become progressively worse since the middle of the Qing Dynasty (1644-1911) - since about 1780 - and so looking at porcelain quality is very important in determining age. 

Concerning age, the most tell tale sign on Chinese porcelain is the bottom and foot of a piece. This is often frustrating when visiting a museum or exhibition because more often than not the bases of pieces are not visible and only such shows as say those put on by the Asia Society or those run by ceramic societies have the sense to display pieces so the bases are visible (they also tend to have the specialized crowd to demand this). Having seen but more importantly felt many bases of authenticated pieces of different periods is (as with all antiques) always best in understanding the differences observable over time and in this way comparisons are possible. In general however, if the thumb is taken and rubbed over the foot of the snuff bottle, the porcelain body should be very smooth and without much granulation. 

New bottles may appear to be of fine porcelain due to a heavy white and translucent glaze which masks the often stoneware and not porcelain body. When the foot is felt on most new pieces the texture could be described as even abrasive in comparison to earlier pieces. Very early pieces of porcelain produced during the Kangxi reign (1662-1722) have a foot which could even be described as silky to the touch, such was the quality and make up of the porcelain body during this time. However, as was stated the likelihood of finding such an early piece is next to impossible and due to the often tiny foot of a porcelain bottle, it may feel smoother than it would if the same porcelain were used on a larger piece and with a larger foot with more surface area. 

A second check to make is that of the enamels or under glaze decoration on the bottle. It is true that there are monochrome bottles however the majority are one of the above mentioned types. Comparing the enamels on larger documented pieces which are not snuff bottles can often lead to an attribution of a date to similarly decorated snuff bottles. Those enamels in famille rose should be pleasantly harmonious in a pastel palette and never harsh in tint. On famille rose pieces, the newer the pieces typically the greater the use of orange in the palette as well and a lack of gold in the details. 

Under glaze blue pieces were executed using cobalt and therefore the color is not always consistent (cobalt is still used, though some pieces use blue transfers particularly on the cylindrical bottles and these lack the following qualities in addition to having what can be observed as innumerable dots under a magnification). In an older piece the decoration should have variation! in color and in particular, there should be "build up" of cobalt, making it darker, at say the base of a line or around the foot of the bottle where the liquid would naturally accumulate. 

The blue of newer pieces lacks the vibrancy of color and often appears flat, having little variation and usually the color borders on a dark navy or in the extreme to a black which is not at all characteristic of 19th century bottles. Regarding the decoration of both under glaze blue and enameled bottles, with landscapes or figures depicted, you should be impressed by the detail and composition of the scene. You should look at the piece and be amazed at how such precision was possible on such a small object - as newer pieces often have coarsely painted and clumsy subjects with little detail. 

Finally you can look at the mark if one is present. Marks so rarely are of the period of the snuff bottle's production that they should only serve as a confirmation of what has been determined by all other signs of age. So often new collectors and dealers find a mark on a piece of porcelain in one of the many books depicting them and then assume that the piece is naturally of the reign indicated by this mark. It is common to find them with the marks of Yongzheng (1723-1735) or Qianlong (1736-1795) but these are almost never of the period and those that are have long ago found their way into museums. Just because of the erroneous marks however, these pieces should not be discounted because they are often of the Jiaing (1796-1820) or Daoguang (1721-1850) periods. Marks should be executed in an enamel in the palette of the piece or are often found in red or under glaze blue. The mark should never appear to have been stamped on the piece as so many new bottles do. Also, just as attention to detail and quality in decoration is important, the precision of the mark's depiction is important and a sloppy mark is indication of either a late date or a piece that may be early but is not necessarily of any quality.