What is a Wine Diamond?
A Wine Diamond, scientifically known as tartrate crystals, potassium bitartrate crystals or more commonly cream of tartar (yes, just like the one used to perfect that meringue), are tiny, crystalline deposits that form when potassium and tartaric acid, bind together to form a crystal. Many winemakers believe crystals are a sign of quality, as the wine endured less processing.
These crystals can be present in either red or white wines, and their formation is linked to temperature, and you may see them under the cork (if it has one) or sitting at the bottom of the bottle. They resemble tiny sugar granules or crystals and if you wished, you could gently decant the wine to separate the wine from the crystals.
Tartrate crystals are completely harmless and do not alter the taste of the wine in anyway.
Wine diamonds can be removed through a process called ‘cold stabilisation’ and is a process winemaker’s use purely for aesthetic reasons. It involves chilling the wine to -6°C for up to a week. This accelerates the formation of crystals, which can be more easily filtered out. What this can also do is strip the wine of some of its lovely aromas and flavours, and affect its ability to age.
So, consider yourself lucky if you find a precious wine diamond in your bottle or glass, it is a sign of minimal intervention and great winemaking!