First let’s define tartrates. You may have heard them called “wine diamonds.” You can find them on your cork, in the neck of the bottle, and in extreme cases floating in the wine itself (or sunk to the bottom). It’s not bad. It’s just not pretty. Some consumers think it’s a “fault.” It’s not. But to prevent any misconceptions or unhappy conversations, many winemakers will stabilize against them.
What these crystals actually are are deposits of potassium and calcium tartrates. It often happens when a wine (that hasn’t been stabilized against tartrates) sees a dip in temperature—tartrates are less soluble at cold temperatures.
