Some of our customers have asked us about crystals they find from time to time in their wine kits. These crystals are known as Wine Diamonds or tartaric acid fall out.

Wine diamonds are crystals sometimes found in the bottom of wine bottles. Wine diamonds, or potassium acid tartrate, is a mono-potassium salt. In its natural state, it is commonly found in many fruits but predominantly in grapes. You may notice these crystals when you remove a wine bottle from your refrigerator or cold storage since it’s cold temperatures that cause diamonds to form. It is entirely natural and is NOT a defect. In fact, it reflects the high quality of the wine.
 
There is a correlation between wine diamonds and the quality of a wine: the longer the grapes hang on the vine, the more wine acid will accumulate in the grape, this wine acid is the building block of wine diamonds. In other words, wine diamonds are an indicator that the grapes ripened for a long time, an important precursor to crafting high quality wines.

Wine diamonds are also a sign of natural fermentation. By natural fermentation we mean the yeast works with the nature sugars present in the fruit and not by adding inverted sugars.

Tartaric acid, the primary acid in all grapes, is one of the components that promotes a crisp flavour and graceful aging in wine. When tartaric acid combines with natural occurring potassium they form potassium bitartrates or cream of tartar. Wine diamonds can be found in both red and white wine, they absorb the red or brown pigments from red wine and in white wine they can look like shards of glass. Wine diamonds are harmless, have no effect on the flavour and only impact the wine visually.

Tartrates can be routinely found in commercially produced wine and considered a sign of quality. The process of tartrate crystal formation is very hard to predict and tends to occur in 100 % pure grape juice wine kits that do not require the addition of inverted sugar.

At Vintner’s Cellar we cold stabilize by chilling your wine to 10C for a week, then filtering. This is a moderate form of cold stabilization therefore; wine diamonds may reoccur. We suggest you store your wine at 55 to 60ºF and only chill down to 45 to 48ºF before serving to try and avoid re-occurrence.