Most scholars believe that the tradition of wearing birthstones descended from the Breastplate of Aaron. In Jewish history, this was a garment worn by priests that was decorated with 12 stones. On the breastplate, they represented the 12 tribes of Israel, and over time came to correspond with the 12 months of the year, or the 12 signs of the Zodiac. While the stones that appeared on the breastplate are not the same stones we associate as birthstones today, the tradition of wearing stones and the belief that they convey power, strength, or protection has continued. Here is some information about the birthstones associated with the fall months of September, October, and November.

The birthstones for September are opal and lapis. Most people associate sapphires with the color blue, and this is the most common and popular color for sapphires, but they can also be found in colors like yellow and and white. Sapphires are the same mineral as rubies, corundum, so when sapphires are red or pink, they are called rubies instead. Sapphires are very hard, almost as hard as diamonds, and do not scratch easily. They are sometimes called the gem of the heavens because they are blue like the sky. Their blue color is also linked with loyalty and faithfulness, and many couples choose sapphires as the stone for engagement rings, with or without diamonds. Lapis is more common and not as expensive, but is the same brilliant color blue. It does not shine like a sapphire, but is dull instead.

October's birthstones are opal and tourmaline. Opals are unusual among gems in that you will find many different colors in a single stone. Most of the world's opals come from Australia, and they are sometimes called rainbow stones to reflect their multicolored nature. Opal is the same chemical composition as quartz, but contains water that refracts light, causing the different colors. Unlike sapphires, opal is very fragile and brittle. As such, a lot of opal jewelry is covered with clear protectants like resin or enamel. Opal becomes more brittle as it loses its water, so it should not be kept in very dry areas for lengthy periods of time. In fact, opal jewelry should be worn frequently, as it can absorb humidity from the skin. Like opal, tourmaline is a multicolored stone, but is a different chemical composition.

Yellow topaz, the birthstone for November, ranges from a warm brownish yellow, to shades with more red and orange. Both the ancient Romans and Egyptians associated topaz with their sun gods, and many believe it has protective powers. Citrine resembles topaz, but is a variety of quartz and is much more affordable.