Wine is fascinating because it's so much more than fermented grapes. The science that goes into wine, and the subtleties of the different grapes and barrels and aging process can make a world of difference on the wine.
And then every once in a while, you come across something you've never experienced before.
When we were in New Orleans, Chris' dad brought a bottle of wine to dinner. The waiter opened the bottle, and when she handed the cork to us, we saw it had little crystals on the bottom:
I was so curious since I'd never seen anything like it. That's why I kept the wine cork to take pictures of and research!
What this actually is is tartaric acid crystals. Commonly known as "wine diamonds" because they're sparkly and hard and occur frequently in wine, they're actually a deposit that grows on the cork as well as the inside of the wine barrels.
"However, tartaric acid plays an important role chemically, lowering the pH of fermenting "must" to a level where many undesirable spoilage bacteria cannot live, and acting as a preservative after fermentation. In the mouth, tartaric acid provides some of the tartness in the wine, although citric and malic acids also play a role." (Wikipedia)
So if you're lucky enough to find some wine diamonds of your own, still feel free to enjoy the wine! And maybe save the cork :)