Glass Lidden Cup
盖杯 (pinyin: gàibēi; literally, "lidden cup“) is a Chinese covered bowl used for the infusion and consumption of tea, first created during the Ming Dynasty.
Prior to Ming Dynasty China, tea was normally consumed from the vessel in which it was prepared. As described by the tea master Lu Yu, this special bowl had to be large enough to accommodate the implements and actions of tea brewing, though compact enough to be held comfortably in the hands for consumption. The term for this versatile piece of equipment was simply "cháwǎn" (茶碗 lit. “tea bowl”). It was during the Ming dynasty that the innovations in both tea ritual and tea preparation gave rise to the gaibei. The Gaibei of the Ming Dynasty and Qing Dynasty were larger than the Gaibei used today for brewing tea for several people. The Gaibei of today are generally smaller and more leaves are used in brewing.
The gaibei is considered by many tea connoisseurs to be the preferred method for brewing teas with delicate flavors and aromas, such as green tea and white tea, although without the lid in these cases. The versatility of the gaibei is also noted in the preparation of oolong infusions because of this particular tea's ability to be infused multiple times, but the gaibei is suitable for any type of tea. The gaibei is important in tea tasting due to its open and glazed surfaces: the former allows the tea to be viewed while brewing, and the latter prevents altering of the flavour and aroma of the tea during brewing. The gaibei consists of a saucer, bowl, and lid. The lid allows the tea to be infused right in the bowl and either be drunk right from the bowl (traditionally using the lid to block the leaves for ease of consumption), or decanted into another container. The gaibei itself can be made from a variety of materials, including porcelain and glass. Gaibei made from Yixing clay are particularly prized by collectors of tea paraphernalia.
Gaibei is the preferred method for brewing green and white teas as the gaibei's porcelain absorbs the heat and does not damage the tea. Gaibeis are less suitable for black teas as the large lid allows heat to escape too quickly during the steeping process. They are especially common in the north of China for enjoying scented teas like jasmine tea.
*Information from Purple Cane, Wikipedia.