October Birthstone: Opal and Tourmaline Guide

October is the only month whose two birthstones could hardly look less alike. Opal holds every color at once and never shows the same face twice. Tourmaline picks one color and commits to it completely. Both belong to October, and choosing between them has less to do with taste than with how the jewelry will actually be worn.

October Birthstone Facts

Hardness is measured on the Mohs scale from 1 to 10. The number matters more than it sounds: everyday dust contains quartz, which sits at 7, so any stone softer than that will slowly abrade with enough contact.

Why October Has Two Birthstones

The birthstone list most jewelers work from today was standardized in 1912 by the American National Retail Jewelers' Association, known now as Jewelers of America. That list has been revised several times since, and the revisions are the reason several months carry more than one stone. December gained tanzanite in 2002. August gained spinel in 2016. October gained pink tourmaline.

Opal came first and still carries the month in most references. Pink tourmaline was added partly for practical reasons: it offers October a stone that takes daily wear without special handling, in a color range that reads unmistakably as a birthday gift. Neither stone outranks the other. If you are shopping for someone born in October, the honest question is which of the two suits the person, not which one is correct. Our month-by-month birthstone finder sets October alongside the other eleven months if you want the wider view.

Opal: One Stone, Every Color at Once

Opal is not a crystal. Where a sapphire or a tourmaline grows in an ordered lattice, opal forms as microscopic spheres of silica that settle into a loose three-dimensional stack, with water filling the gaps. Water content runs anywhere from 3 to 21 percent by weight, and most gem opal sits between 6 and 10 percent. That water is the source of both opal's beauty and its particular needs.

What creates play-of-color

When those silica spheres are close to uniform in size and neatly arranged, they diffract light the way a very fine grating does, splitting it into spectral flashes that shift as the stone moves. Gemologists call the effect play-of-color, and it is the single property that separates precious opal from common opal, which has the same chemistry but no ordered structure and therefore no fire.

Sphere size determines which colors appear. Smaller spheres favor blues and violets, which is why blue and green play-of-color is the most frequently seen. Larger, more consistent spheres are needed to produce red, which is why strong red flash commands the highest prices in the opal trade.

The main types of opal

• White or light opal: a pale body color with pastel flashes. The most widely available and the most familiar look.
• Black opal: a dark grey to black body color that makes the spectral flashes read far more vividly. Historically associated with Lightning Ridge in New South Wales.
• Crystal opal: transparent to semi-transparent, with play-of-color visible through the body of the stone rather than sitting on it.
• Fire opal: an orange to red body color, often from Mexico. Some fire opal shows play-of-color and some does not, and both are correctly called fire opal.
• Boulder opal: a thin natural seam of opal still attached to its ironstone host rock, cut so the host forms a dark backing.
• Doublets and triplets: assembled stones. A doublet bonds a slice of opal to a dark backing; a triplet adds a clear protective cap. Both are legitimate, both must be disclosed, and both need extra care around water and heat because of the adhesive layer.

Australia remains the reference point for white and black opal. Ethiopia has become a major modern source, and much Ethiopian material is hydrophane, meaning it absorbs water and can temporarily turn cloudy or transparent if submerged. That trait is worth knowing before you wear an opal into a swimming pool.

Opal at this price point is almost always lab-created, and the label on each piece says so plainly. Created opal shares the silica structure and the play-of-color of natural opal while offering a far more consistent pattern, which is why it works so well in matched pairs like studs. You can see the full range in our Opal collection, or browse by piece in opal rings, opal earrings and opal necklaces.

Tourmaline: A Single Mineral Family in Every Hue

Tourmaline is not one mineral but a group of boron silicates, and the gem varieties people actually buy belong mostly to the species elbaite. The group's range of color is close to unmatched in gemstones. Trace elements decide the outcome: manganese pushes toward pink and red, iron toward green and blue, copper toward the electric blue-green of Paraiba tourmaline.

Two of tourmaline's quirks are worth knowing because you will notice both. The first is strong pleochroism, meaning the stone shows different color saturation along different crystal directions. A cutter has to orient the rough deliberately so the best color faces up, and that orientation decision does more for a tourmaline's beauty than carat weight does. The second is that tourmaline is pyroelectric and piezoelectric: it develops a small electrical charge when its temperature changes or when it is put under pressure. This is the reason a tourmaline that has been sitting in sunlight or against warm skin picks up dust and lint, and it is a curiosity rather than a problem.

Why pink tourmaline became October's alternate

Pink is the variety that carries the month. Strongly saturated pink to red material is traded as rubellite, while lighter blush and bubblegum tones are sold simply as pink tourmaline, and the boundary between the two is a judgment call rather than a defined line. At 7 to 7.5 on the Mohs scale, pink tourmaline is harder than opal, harder than peridot and harder than the quartz in household dust, which makes it genuinely practical for a ring in daily rotation.

Most gem tourmaline comes from Brazil, particularly Minas Gerais, with significant production from Nigeria, Mozambique, Madagascar, Afghanistan and Sri Lanka. Maine and California have produced fine pink tourmaline for well over a century.

A stacking ring is a useful way to start with tourmaline, because the stone is tough enough that you can wear it alongside other bands without worrying about the softer stone in the group. For a single piece that does more work, our pink tourmaline rings and the broader pink gemstone jewelry collection are the places to look.

Opal or Tourmaline: How to Choose

For a gift, we tend to work backward from the recipient's habits rather than forward from the stone.

• Choose opal when the appeal is the stone itself. Nothing else in jewelry moves the way opal moves, and for a pendant or a pair of earrings the durability question barely arises. Opal is also the better answer when someone already owns plenty of transparent colored stones and wants something that reads differently.
• Choose pink tourmaline when the piece will be worn without thinking about it. A tourmaline ring survives washing up, car doors and gym bags in a way an unprotected opal will not. It is also the easier colour to match to an existing wardrobe of rose gold or sterling silver.
• Choose both when the budget allows. A pink tourmaline ring paired with opal studs covers October twice, and the two stones sit together surprisingly well because opal's pastel flashes usually include pink.

One practical note on size. Because opal is cut as a cabochon rather than faceted, a 10mm opal reads far larger on the hand than a 10mm faceted stone of the same measurement. If someone prefers understated jewelry, a smaller opal goes further than you would expect.

Pieces that combine pink tourmaline with diamond accents land well for milestone birthdays, and they sit naturally in our gifts for her and mother's and family jewelry collections.

Choosing by Piece: Rings, Earrings, Pendants and Bands

The same stone behaves differently depending on where it sits.

• Rings take the most impact of any piece of jewelry. Tourmaline handles it. Opal can too, provided the setting protects the girdle, which is what bezels, halos and flush inlay all do.
• Earrings are the most forgiving mount in jewelry. They almost never strike anything. Any opal works here, including larger stones you would hesitate over in a ring.
• Pendants sit close to neutral. A pendant on a longer chain swings more and makes contact with buttons and zips, so a bezel is worth having on an opal pendant you plan to wear often.
• Wedding and anniversary bands suit inlay. An inlay band sets the opal flush with the metal surface, so there is no raised edge to catch, and the stone is supported along its whole length.

Stainless steel deserves a word here. It is harder than silver or gold, it does not need plating, and in an opal inlay band it gives the stone a rigid surround that resists the flexing a softer metal allows. Pieces like these turn up in birthstone rings, and the gold options sit in gemstone necklaces.

Settings and Metals That Protect a Softer Stone

With an October stone, the setting does real work rather than just holding the gem in place.

• Bezel: a continuous metal rim around the girdle. The most protective common setting, and visually it suits a cabochon opal better than prongs do.
• Halo: a ring of small accent stones encircling the centre gem. The halo sits slightly proud of the main stone, so the accents take knocks that would otherwise land on the opal.
• Inlay: stone set flush into a channel in the metal. No raised edge at all, which is why it is the standard for opal bands.
• Prongs: fine for tourmaline. On opal, prefer four or six broader prongs over many fine ones, since each prong is a point of pressure on a softer stone.

On metal, most of our October pieces are sterling silver, usually rhodium-plated. Rhodium is a thin, very hard white layer that resists tarnish and brightens the silver beneath it; it does wear thin over years and can be reapplied by a jeweler. Rose-tone plating is worth considering for pink opal and pink tourmaline, because the warm metal repeats the stone's colour instead of competing with it.

Blue opal is a reminder that October's stone is not only white. Lab-created blue opal gives the same shifting flashes against a cooler body colour, which reads as more modern on the hand. Browse more of these in birthstone earrings, sterling silver jewelry or pieces under $100.

Caring for Opal and Tourmaline

Neither stone is difficult. Both have one firm rule.

Opal. Clean it with warm water, a drop of mild soap and a soft cloth, then dry it gently. Keep opal out of ultrasonic cleaners and steam cleaners entirely. Both apply the two things opal tolerates least, which are vibration and rapid temperature change, and the risk is crazing: a fine network of surface cracks that cannot be polished out. Avoid leaving opal in very dry heat for long periods, skip the solvents in hairspray and perfume, and take an opal ring off before cleaning with bleach or ammonia. Store it away from harder stones so nothing scratches the surface.

Pink tourmaline. Warm water, mild soap and a soft brush handle everything tourmaline needs. Skip ultrasonic and steam here too, since many tourmalines carry liquid-filled inclusions or fine fractures that vibration can open. Expect the stone to collect dust when it is warm, and wipe it with a soft cloth rather than treating it as a cleaning problem.

Both. Store pieces separately in soft pouches or a lined box. The simplest habit that protects jewelry is also the oldest one: put it on last when you dress, and take it off first when you undress.

Natural, Lab-Created and Imitation: Reading the Label

Three different things get called opal in jewelry, and the difference matters.

• Natural opal formed in the ground over a very long time. Every stone is unique, and pattern and body colour drive the price.
• Lab-created opal is grown under controlled conditions and shares natural opal's silica structure and play-of-color. Patterns are more regular and more repeatable, which is an advantage in matched earrings and inlay work.
• Imitation or simulated opal is glass, resin or plastic made to resemble opal without matching its composition. Opalite is the best known example.

United States Federal Trade Commission guidance requires that lab-created and imitation stones be clearly disclosed, so a listing that says "created opal" is telling you exactly what you are buying. Our product titles carry that language, and the same convention applies to every other stone we sell. If you want to see the material on its own, we keep lab-created loose gemstones and natural gemstone jewelry in separate collections. For a primer on how stone weight is described, our note on carats covers the basics.

October Birthstone Questions, Answered

What is the birthstone for October?

October has two. Opal is the traditional October birthstone, and pink tourmaline is the modern alternate. Both are recognised, and either one is a correct choice for an October birthday.

Is opal or pink tourmaline the real October birthstone?

Both are. Opal appeared on the standardized 1912 list and still carries the month in most references. Pink tourmaline was added later as an alternate, largely because it offers an October stone that handles daily wear more easily. Pick by the wearer, not by precedence.

Can you wear an opal ring every day?

Yes, with the right setting. Opal sits at 5 to 6.5 on the Mohs scale, so it needs protection at the edges. A bezel, a halo or a flush inlay band all shield the stone's girdle. An opal in high fine prongs is better kept for occasional wear, and a pink tourmaline ring is the easier answer if the piece will never come off.

Can opal go in an ultrasonic cleaner?

No. Ultrasonic and steam cleaning both subject opal to vibration and sudden temperature change, which can cause crazing, a fine network of surface cracks that cannot be polished out. Assembled doublets and triplets are at even greater risk because the adhesive layer can fail. Use warm water, mild soap and a soft cloth instead.

Is pink tourmaline the same as rubellite?

Rubellite is the trade name for tourmaline in strongly saturated pink to red, so all rubellite is pink tourmaline but not all pink tourmaline is rubellite. There is no official saturation threshold between the two, which is why the same stone is sometimes described either way.

Why does my tourmaline attract dust?

Tourmaline is pyroelectric and piezoelectric, meaning it develops a small static charge when its temperature changes or when it is pressed. A stone warmed by sunlight or skin will pick up lint and dust. It is a genuine property of the mineral rather than a defect, and a soft cloth takes care of it.

What is created opal, and is it a lesser stone?

Created opal is grown in a laboratory and shares the silica structure and play-of-color of natural opal. It is a different product rather than a lesser one: its pattern is more consistent, which makes it the better choice for matched pairs and inlay, and every listing states clearly that the stone is created.

Related Reading

October sits between two more months with a choice of stones, and the stones either side are worth a look if you are shopping for a family.