February is the birthstone month of the glorious purple amethyst, and today’s tiara features some of the largest amethysts you’ll ever see in a diadem: the Tavistock Amethyst Tiara.

This piece has a two-step creation story. The largest amethyst and its surrounding diamond honeysuckle setting came first, in the early years of the nineteenth century. Around 1870, that piece was integrated into a new tiara, featuring grape leaves and more large grape-colored amethysts.

It’s not entirely clear which member of the family had the piece made; in 1870, the title was held by William Russell, the 8th Duke of Bedford, but he was never married and would therefore probably not have had any need for a tiara. Perhaps it was the man who would succeed him, Francis Russell, who had the piece made? Or maybe it was Francis’s son, George? After all, George became the Marquess of Tavistock (that’s the subsidiary title of the Bedford dukedom) when his father inherited the dukedom in 1872. The tiara takes its name from the Tavistock title — that might be the biggest hint we have.

Exact provenance aside, the tiara is a lovely piece with a clear symbolic meaning. The overall effect of the grape leaves and the wine-colored stones is that of a tribute to Dionysus, the god of wine — which makes perfect sense, as the word “amethyst” roughly translates to “not intoxicated” in the original Greek. The Greeks believed that those who wore the stone were protected against drunkenness; medieval Europeans thought that wearing amethysts protected you from fits of bad temper. (Really the same thing, I suppose.) Today, the piece is still owned by the family, and I assume each marchioness and duchess in the last century who has worn it has done so proudly, calmly, and (ahem) soberly.