Are Diamonds a Wine’s Best Friend?

It seems like an odd question to ask. Wine and diamonds are often grouped in with things of finery, so why wouldn’t diamonds be a wine’s best friend? But, wait, what does that mean?

What are wine diamonds? And why is there something in the bottom of my glass?

There are conflicting perspectives on whether or not wine diamonds are a flaw or a positive attribute, but before we get into cold filtration, potassium bitartrate, and whether or not those strange little crystals in your glass are a good thing or a bad thing, it’s essential to know what exactly a wine diamond is.

As many plants do, grapevines thrive in Potassium rich environments, like that of the rolling hills that surround Rolling Forks Vineyards. They also produce a fruit that becomes more acidic as it reaches a premium. In some environments, grapes are able to reach a state of over-ripeness that leads to lower acidity, meaning some areas of the world can produce wines that aren’t necessarily a lower quality but still lack formations of Potassium bitartrate crystals.

When the vines pull nutrients from such rich soil, the combination of the Potassium and the high acidity of the grapes causes the formation of tartrate crystals called Potassium bitartrate. Or, more simply put, cream of tartar. When chilled, these crystals cluster together and form “wine diamonds.”

Now that we know what wine diamonds are and how they’re formed, we can discuss their pros and cons. Are they a “bad thing?” Are they a sign of a flaw in the wine’s making? Many winemakers and sommeliers disagree with the perception that wine diamonds are a flaw. Others see it as something that is visually displeasing. Because of this, some wineries, particularly those in Minnesota where the cold climate and potassium-rich soil lead to increased numbers of wine diamonds, put their wines through a process called cold stabilization.

Cold stabilization begins with seeding the wine with cream of tartar. This seems counterproductive on the face of it, but this causes the crystals to form larger clusters that are more easily filtered out later in the process. Once cream of tartar is added to the wine, the temperature is dropped to 28 degrees Fahrenheit and the wine is then chilled at just below freezing temperatures for two to three weeks. After the wine is chilled, it’s then filtered while still cold. The large clusters are removed, and any Potassium bitartrate remaining is reabsorbed.

At Rolling Forks Vineyards, this process is typically done in the winter time after fermentation is complete.

At first glance, one might think there is nothing but pros to this process. Visible crystals are removed from the wine– giving it a “cleaner” look to some customers– and the shelf life is improved. Why wouldn’t you want these things? Of course, it’s a process that should be done!

But cold stabilization doesn’t just remove wine diamonds. It removes aromatics and subtler notes from the wine’s flavor profile, leading to a duller smell and a difference in feel on the palate. If you were to take two wines from the same harvest of the same year of the same grape variety, put one vintage through cold stabilization, and leave the other without, the wine that wasn’t stabilized would potentially have a different profile and mouth feel. The process of cold filtration/cold stabilization can create a loss of aromatics and change in the flavor profile of a wine. At the end of the day, the pros and cons of cold stabilization are debatable. With the general consensus to perform the task of cold stabilization.

So are diamonds a wine’s best friend? As many people as would say wine diamonds are essential to prove the true quality of a wine, just as many find them visually unappealing. It depends entirely on your customer and what best suits their taste. But, overall, wine diamonds are a natural process and a sign of wonderfully grown grapevines.