Rare pink diamonds are once again making eye-catching appearances at prominent jewelry auctions worldwide, and it’s not just a color for Valentines Day gifts.

Tanzanite, December’s birthstone, is found in the shadows of the majestic Mount Kilimanjaro in Tanzania, the only commercial source for the gemstone.

Turquoise, the December birthstone, has a distinct blue or greenish-blue color because it contains copper, and is most commonly found in China and the U.S. southwestern states Arizona, New Mexico, Colorado and Nevada.

Topaz, November’s birthstone, is a mineral species that naturally occurs in a range of color, including various reds, pinks, purples, yellows, oranges, browns, and more rarely, pale blue. Topaz in yellow and reddish brown are commonly heated to create more desirable pink gems.

November’s birthstone, citrine, comes in the colors of citrus fruits, ranging from deep reddish orange, reminiscent of Madeira wines, to pale and saturated yellow hues. In fact, its name is derived from the French word “citron,” which means “lemon.” Citrine’s optimistic colors bring to mind the warmth of mid-day sunshine.