Blue is a cool color, so it seems surprising to me that it is the color for December, even though December is a cold month. Maybe it was chosen to cool the Christmas season a little, or as an antidote to so much red and green. My guess is that the choice is buried in the depths of history. Turquoise and or topaz are included on some lists of the 12 stones on the Breastplate of Aaron. Each stone represents one of the 12 tribes of Israel. And, blue and silver are the colors of Hanukkah which begins at sundown on Tuesday, December 20. Perhaps Hanukkah colors, or the Breastplate of Aaron, are the derivation of blue as the color for the month of December. I will also concede that it is possible that blue was chosen because December is generally a cool month, and the lead-in to more. Well, I don't know, so we will move on to some of the lore for turquoise and blue topaz.
Many ancient people considered turquoise to be a sacred stone which protected its owner from evils and ill health. For those reasons, it was one of the first gems to be used in jewelry. Turquoise is mined in the southwest of the US and Native Americans from that region use it in their gorgeous jewelry, which is often symbolic.
Blue topaz is a hard stone and has many of the same properties as golden topaz (November's birthstone). Ancient lore holds that blue topaz has special cooling properties such as cooling a pot of boiling water when it is thrown in. (This is something I would never do with any gemstone.) It is a symbol of love and fidelity, which seems odd for a gem with cooling properties.
I guess this is another of the weird contradictions associated with December's birthstones.
I find it interesting that I just completed my Repeat Performance (November's knit along) sock project and guess what--tthe socks are the cool blue color of December. In spite of the fact that cool blue is not a favorite, I love the socks. I am getting used to the color, but I love the yarn and the pattern-so I am very happy with the socks. (I might not even give them away as quickly as possible, which had been my original plan.)