Wanda Haynes,
Certified Sommelier
What are wine diamonds?
When wine has bits of crystals in the bottle or in the glass this is known as “wine diamonds” and they resemble unfaceted diamonds.
How do the diamonds form?
Tartaric acid and potassium are found in all grapes. When the two clump together under cold conditions they form potassium bitartrate crystals and settle to the bottom of the bottle.
Be mindful that the wine diamonds are completely natural and don’t affect the quality of the wine.
Europeans are more familiar with wine diamonds and are not alarmed to see them.
Americans are accustomed to clear wine and when something is in the glass or bottle it creates panic.
How to prevent wine diamonds?
The tartaric acid and potassium are natural components of grapes and can’t be removed. To make sure crystals aren’t formed after being sold the winemaker forces the crystals to form at the winery.
This is known as “cold stabilization” and predominately used for white and rosé.
Red wine can also form wine diamonds, although less likely due to the warm temperatures they are produced under.
The stainless-steel fermentation vessel for the wine has a cooling system.
After the fermentation is complete the vessel is plunged to near freezing for 3 days to force the crystals to form.
The crystals stick to the sides of the vessel, and they remain in the vessel.
If they are found in a glass just ignore them and enjoy the wine.