Tartaric acid is the natural ingredient which is existing in grapes or other fruits (such as bananas or tamarind, sweet angle), also the main organic acid of wine. Crystals are formed at low temperatures. In north European, winter is long and cold, wine in the ripening process, containing tartaric acid is easy to crystallization, so the crystal called wine "diamond". Wine cellar will wait until next spring and summer, climate warming, the wines are slightly filtered and bottled. At the same time, people will scrape off tartaric acid crystal which are attached in barrel and fermentor. In areas with warm climates, generally wine does not crystallization, unless keep the wine in low temperature.