Log In / Join Now

Ask Dr. Vinny



Do you have a question for Dr. Vinny? Ask it here...

Dear Dr. Vinny,

I’ve discovered that white crystals have formed in some of my wines. What are they?

—Rupesh. Nepal

Dear Rupesh,

I assure you that it’s perfectly normal to come across crystals that look like chunks of salt or rock candy in your wine. Tartrate crystals are a harmless, naturally occurring byproduct of winemaking; they might taste a little sour if you try eating them. They typically collect on the cork or at the bottom of a wine bottle. They are sometimes referred to as “wine diamonds,” a lovely way to try to convince people not to worry about them. Another way to consider their harmless nature is to remember that they’re the same substance used to make cream of tartar, which keeps my snickerdoodle cookies light and airy.

Tartaric acid is one of a few types of acid found in wine grapes. Through the process of fermentation and winemaking, it tends to settle out of the wine. They're sensitive to cold temperatures, and some wines actually go through a “cold stabilization” process to separate the tartrate crystals out before bottling. Sometimes wine drinkers might confuse them for broken glass, so it’s just a cosmetic treatment.

—Dr. Vinny

Wine Basics

We break down the basics—how to taste, serve, store and more. Plus:
» Maps of major wine regions
» Grape variety characteristics

How-to Videos

Learn to taste wine like a pro, pull a cork with flair, get great wine service in a restaurant and more

Wine Spectator School: All courses are FREE for WineSpectator.com Members

Learn from the experts and get the most out of each sip. Take one of our online courses or take them all—from the ABCs of Tasting to in-depth seminars on Food Pairing, California Cabernet, Bordeaux, Tuscany, Sensory Evaluation and more.

Browse our course catalog
Check out the professional wine sales and service courses
Learn Wine Forum: Got questions? Get answers


WineRatings+ app: Download now for 340,000+ ratings.