Wine diamonds are tartrate crystals that form in some wines. They may float to the bottom of the bottle or adhere to the bottom of the cork as seen here. This was the first time I have seen them. It was an exceptional bottle of red wine. They are not harmful and wine connoisseurs appreciate the wine diamonds as evidence of the wine’s authenticity and traditional winemaking techniques. All of this was new to me when we saw them this week in a very good bottle of Cabernet that a friend brought.
