According to Kalmbach Publishing Company, (See Reference 1) ancient peoples believed that particular gemstones had more power in particular months. This led to the custom, enjoyed by so many people today, of buying birthstones. Others may scoff at the whole notion of birthstones and point out that gemstone retailers may have had more than a little to do with the marketing of the concept.
According to Bernardine Fine Art Jewelry, the modern birthstone for January is garnet. February's is amethyst. Aquamarine is the modern birthstone of March. The month of April has diamond. Those born in May have emerald as their modern birthstone. June has two stones, pearl and moonstone. Those born in July have ruby as their modern birthstone. August's stone is peridot. Sapphire is the birthstone of those born in September. October boasts two stones, opal and tourmaline. November also has two, both yellow in color, yellow topaz and citrine. There are three modern birthstones for December. These are blue topaz, turquoise and tanzanite.
Kalmbach Publishing Company list secondary birthstones too,. January's is rose quartz. February's is onyx. For March birthdays, it is bloodstone. April has crystal quartz or rock crystal. The secondary birthstone for May is chrysoprase. June's is moonstone. Carnelian is July's. Sardonyx is the stone of August. September's is lapis lazuli. Pink tourmaline is the stone for those born in October. November's is lemon quartz. Blue topaz is December's stone.
January's mystical birthstone is emerald. February's is bloodstone. Jade is March's mystical birthstone. Opal is April's. Sapphire is the stone for May. For June, it is moonstone. Like its modern birthstone, July's mystical birthstone is ruby. August's birthstone is diamond. The stone for September is agate. Jasper is October's mystical birthstone. Pearl is November's. For December, the mystical birthstone is onyx.
Ayurvedic birthstones relate to a system of traditional Indian medicine known as Ayurveda. The stone for January is garnet. February's stone is amethyst. Bloodstone is the stone of March. Diamond is the stone of April. The month of May's stone is agate. Pearl is June's. Like its modern and mystical birthstones, July's Ayurvedic birthstone is ruby. Sapphire is August's stone. September's is moonstone. Opal is October's. The stone for November is topaz and the stone for December is ruby.