These crystals can develop over time in a bottle of wine, especially if the wine is of high quality and has been stored at a very cold temperature and then brought back to room temperature and chilled again.
This can happen at any point in the distribution cycle – during shipping, at the distributor, at the retail store, or at the consumers premise. The crystals develop from tartaric acid, which is found naturally in grapes.
This is actually the same substance that cream of tartar, often used in baking, is made from.
A bottle of wine with crystals inside is still perfectly drinkable. White wines, such as our German Rieslings, do not need to be decanted. Instead, you can strain the wine or simply pour it slowly and carefully to avoid transferring the wine crystals to the glass.