Good news! She isn't going to die from drinking the wine! That "stuff" has a name - tartaric acid. Tartaric acid is an organic acid that naturally occurs in several plants, especially found in grapes. It can take form of a creamy residue, tiny crystals or flakes. You can place it on your finger tips and it will dissipate from the heat from your body. Taste it and it has the familiar taste and texture of "Sweet Tart" candies, but without the sugar. When the creamy residue dries on the bottom of the cork from a red wine, it will take form of tiny amethyst-looking crystals. Those sparkly little crystals, known as "wine diamonds", means nothing more than a natural evolution of tartaric acid in the wine. As the wine ages, tartaric acid (potassium bitartrate) can no longer be dissolved and so it solidifies. This acid doesn't hurt a thing and chemically it can create an environment where spoilage bacteria cannot live and can also act as a natural preservative.
And have you noticed clear crystals in the bottom of a bottle of white wine that has been in the refrigerator for awhile? No - - it isn't broken glass. That is also tartaric acid and some wineries will place the white wine in cold stabilization to prevent the crystals from appearing. So naturally a few might show up if you do your own stabilization in the fridge - or more like you forgot the white wine was stuffed in the back of your refrigerator.
Are traces of tartaric acids in wine considered a fault? Absolutely not! In our earlier New World wines, we have not seen many traces of tartaric acids as many of those wines have been overly fined and processed. In America, as we often do, we tend to over process something until it is perfect! In the mean time, America's largest producers of wine have been messing with the wine’s colloidal structure all in the name of "visual perfection." As the USA has progressed in the last 30 years in their winemaking craft, producing quality wines, chances are great that the wine consumer is seeing more traces of tartaric acids in their wines. Especially those wines that have been given some age. Many winemakers will tell you that the signs are tartaric acids are signs of high quality wines. And yes, it is the same "stuff" that you see in the bottom of a wine that has aged - sediments.
And one more thing - have you ever used a substance found in the spice aisle at the market labeled as "Cream of Tartar?" Originally discovered by the French, bakers use cream of tartar to give volume to meringues, souffles, angel food cakes and Snickerdoodle cookies. Well, those merchants of cream of tartar actually scoop the potassium bitartrites from the bottom of empty large holding tanks that once held wine.
"Wine diamonds" are indeed an indicator that grapes were given extra hang time on the vine for maximum sweetness and acids. It is also an indicator the winemaker crafted the wine slowly and very carefully. Therefore, when you are opening a bottle of wine and find the signs of wine diamonds, you can be sure that you are opening a great bottle of wine and most of all - - at the right time. The only bad thing I can say about wine diamonds is that you cannot wear them on a finger. Cheers!