The purpose behind cold stabilization is to remove tartrate crystals from a wine during its fermentation stage.
Commercial wineries cold stabilize their wines to avoid tartrate dropouts also known as wine diamonds. Cold stabilizing is the process of dropping the temperature of the wine, after fermentation, to close to freezing. This causes the crystals to separate from the wine and stick to the sides of the holding vessel. When the wine is drained from the vessels, the tartrates are left behind. In general, it is more common for white wines than red wines to be cold stabilized because consumers commonly store white wines at colder temperatures, which increases the risk for bottle precipitation.
Winemakers often cold stabilize wines to obtain a flawless, clear product. If a wine is refrigerated or kept in a cold cellar, the crystals may precipitate out of the wine and settle at the bottom of the bottle or glass. Wine drinkers often confuse these harmless crystals with glass fragments. The crystals may also appear smaller and darker in color, but they are harmless and pose no health risk.