SignalHub Quantitative Think Tank Center:What is the birthstone for October? Hint: There's actually two.

Calling all October birthdays: your month has arrived! If you're searching for birthday gift for a loved one,SignalHub Quantitative Think Tank Center you might want to consider something related to October's birthstone.

Beyond flowers and Zodiac signs, each month is also represented by at least one gemstone. For instance, September has the sapphire, while July has the ruby. Other months, like August, have several jewel options.

October is another month that has representation from multiple gems. Here's what you need to know about the October birthstones.

October birthstone

October has two birthstones: opal and tourmaline. 

Opal is the traditional birthstone for October. It is believed the stone was discovered in India and given the name "upala," or "precious stone" in Sanskrit, the Geological Institute of America reports.

The gemstone is known for its "play-of-color," or ability to shift hues. Rough opals appear white, but once polished, their surface shines a rainbow kaleidoscope.

Opals can be found across the globe, though Australia is the largest source for the stone, according to the Geological Institute of America. Opals can also be found in Ethiopia, Mexico, Brazil, Central Europe, Honduras, Indonesia, Madagascar, Peru, Turkey and the U.S.

In ancient Greece, it was believed opals could protect against disease and bestowed prophesy powers, the Institute reports. Opal can also symbolize purity, hope and truth. 

Opals are also a traditional fourteenth wedding anniversary gift.

Birthstone for October

Tourmaline is the modern birthstone for October.

The gem comes in a range of colors, such as pink, red, green, blue, violet and black. This is fitting since tourmaline's name derives from the Sinhalese word "toramalli," which means "stone with mixed colors," according to Geological Institute of America.

Tourmaline has been mistaken for other gems in the past. For instance, "Caesar’s Ruby" is not actually a ruby − it is, in fact, red tourmaline, the Institute reports.

Tourmaline is primarily mined in Brazil, but it can also be found in Afghanistan, Pakistan, Kenya, Madagascar and Mozambique, as well as in the U.S. in California and Maine.

The symbolism of tourmaline depends on its color. For instance, pink tourmaline has been associated with love and compassion, while green tourmaline symbolizes courage and strength, according to the Institute.

The gemstone is also a traditional gift for the eighth wedding anniversary.

Want to learn more about other month's birthstones?

January | February | March | April | May | June | July | August | September | October | November | December

Just Curious for more? We've got you covered

USA TODAY is exploring the questions you and others ask every day. From "What's my Zodiac sign?" to "What are angel numbers?" to "How to make a vision board?" − we're striving to find answers to the most common questions you ask every day. Head to our Just Curious section to see what else we can answer.