Porcelain InstrumentsPorcelain, which can superficially resemble glass, is essentially a kiln-fired clay. Unlike glass, which is formed when it is molten hot (over 650C/1200F), porcelain/clay is formed at room temperature and then baked. The methods of working porcelain, as well as its chemical and physical properties, are quite different from glass.
Porcelain musical instruments have their own long history, and predate musical instruments made of glass.
I haven't been able to find any example of a porcelain instrument played with the 'wet finger around the rim'. (And although modern wine goblets made of glass which musically work are extremely common, the author has yet to find a single porcelain wine goblet that works musically. The author does have a small porcelain wine-glass that pitifully 'tries' to sing—and being the 'trained professional' he finds it easy to make a glass sing if it's able. )
The following list only includes porcelain cups (and excludes, for example, wind instruments made of porcelain like the ocarina). All are played with mallets or sticks. Some are tuned with water. None are played with the wet-finger-around-the-rim.
The Japanese "Hi"
The 'Hi' is essentially a porcelain teacup. "Its use was suggested by the sound of drinking cups when accidentally struck."1 No mention of more than one 'hi', and no mention of water tuning.
The Chinese "Fou"
The 'Fou' is essentially a clay urn, struck with a wooden or bamboo stick.2 No mention of more than one 'fou', and no mention of water tuning.
The Chinese "Shui Chan"
The Indian "Jâlatharángini"
The Indian Jâlatharángini appeared perhaps around 700 CE. It consisted of a set of porcelain cups tuned with water, and was played with sticks covered with felt or tipped with cork. 5
The Arabian "Tusut"
Played with sticks. The Persian Ibn Ghaybi describes a set of 'musical bowls' made of earthenware, whose notes were determined by the amount of water in each bowl. An author of the 9th/15th century describes a set of kizan (cups) and khawabi (jars) and their water content.6
A Persian Porcelain Instrument
An interesting example of playing porcelain cups is found in The Voyages and Travels of the Ambassadors from the Duke of Holstein to the great Duke of Muscovy and the King of Persioa 1633–39, written originally by Adam Olearius, rendered into English by John Davies:
We were invited to sit down, and to eat of the fruit and conserves which were brought in, during which we had the divertisement of musick and dancing. And as a further honour to us, the Patriarch was sent for, who came in immediately, having about him a cassock of water'd chamlet of a violet colour, and attended by two priests clad in black, with caps on their heads. He was no ill company: but the second of the two bretheren, whose name was Elias—by, made the best sport of any of the company. For, to heighten the divertisement of the ambassadors, he would needs play on the tamera, which is an instrument used by the Persians instead of the lute: and then, he called for seven porcelane cups, full of water, and striking them with two little sticks, he accorded them with the lute.7
413th century Ma Tuan does not mention water tuning, but 20th century Moule says they were "probably containing different quantities of water", yet offers no evidence to support this assertion—they could just as easily simply be different sized cups.