Birthstones by Month: A Complete Guide
If you are buying a gift, helping a friend pick a stone, or just curious about the gem assigned to your month, this guide is for you. Every month has at least one official birthstone. Some have two. Some have three. The traditions go back at least to ancient Roman times and have shifted across centuries. This is the complete and honest version.
We are James and Deborah, and we have run Crystal Empire Gems in Grass Valley, California since 2015. Birthstones are some of our most-asked-about gift purchases all year long. Here is what we tell people for each month, including some honest notes on costs and alternatives.
A brief history of birthstones
The concept of birthstones likely traces back to the twelve stones in the high priest's breastplate described in the Hebrew Bible, and later to the twelve gates of the New Jerusalem in Revelation. By the Middle Ages, European tradition matched specific stones to the twelve signs of the zodiac and the twelve months.
The modern American birthstone list was standardized by the National Association of Jewelers in 1912 and has been updated several times since. The most recent additions came in 2002 with tanzanite for December and 2016 with spinel for August. Different countries sometimes use slightly different lists. The British, Indian, and Tibetan lists all vary from the American one.
Most months have a traditional stone (older tradition, often more expensive), a modern stone (the 1912 standard, often more affordable), and sometimes an alternate stone. We will note each.
January — Garnet
Garnet is the deep red silicate that has been used in jewelry for thousands of years. Egyptian pharaohs wore it. Roman seal rings used it. The Bohemian garnet jewelry of the 1800s is still collectible today.
Garnet comes in many colors despite its red reputation. Pyrope is the deep red. Almandine is darker. Spessartine is orange. Tsavorite and demantoid are green. Pyrope and almandine are the most common for January gifts.
Mohs hardness: 6.5 to 7.5. Suitable for daily-wear jewelry.
February — Amethyst
The purple variety of quartz. Our amethyst guide covers the geology and the long history in detail. Affordable, beautiful, and durable enough for any jewelry. February birthdays are some of the easiest birthstone gifts to shop for.
March — Aquamarine (modern) / Bloodstone (traditional)
Aquamarine is the pale blue beryl, the same mineral family as emerald and morganite. The color ranges from very pale to a deeper sea-blue. Most aquamarine is heat-treated to enhance color. Mohs 7.5 to 8.
Bloodstone is a dark green chalcedony with red iron oxide spots. The traditional March birthstone, less commonly used in modern jewelry but with a long history in carved seals and amulets.
April — Diamond
The most famous gemstone in the world. Pure carbon in cubic crystal form. Mohs 10, the hardest natural mineral. Diamond is the only natural mineral that scores a perfect 10 on the hardness scale.
April is the most expensive birthstone month. Diamond alternatives include white sapphire, white topaz, and moissanite (a lab-created mineral that looks remarkably similar at a fraction of the cost). For non-diamond April gifts, herkimer diamond (which is actually a clear quartz from New York) is a beautiful and affordable option.
May — Emerald
Green beryl. One of the four cardinal gems alongside diamond, ruby, and sapphire. Mohs 7.5 to 8 but more brittle than the hardness number suggests because of natural internal inclusions.
Most emeralds are oil-treated to fill cracks and enhance clarity. The treatment is permanent and accepted in the trade if disclosed. Quality emeralds are among the most expensive gemstones on the market.
More affordable May alternatives include green tourmaline, green aventurine, peridot (the August stone, but a similar green), and chrome diopside.
June — Pearl, Moonstone, and Alexandrite
June has three official birthstones. Pearl is the classic, organic in origin, formed inside oysters and mollusks. Mohs 2.5 to 4.5, very soft, requires careful care.
Moonstone is the second June birthstone. Our moonstone guide covers the geology in detail. Often the most affordable of the three.
Alexandrite is the rarest and most expensive of the three. A color-change variety of chrysoberyl that appears green in daylight and red under incandescent light. Genuine alexandrite is one of the most expensive gem materials on earth. Most commercial alexandrite is lab-created.
July — Ruby
The red variety of corundum, the same mineral family as sapphire. Mohs 9, second only to diamond in hardness. Ruby has been one of the most prized gemstones in the world for thousands of years.
Quality ruby is expensive, particularly Burmese ruby with the deep red color called pigeon blood. More affordable July alternatives include garnet, red spinel, and pink tourmaline.
August — Peridot, Spinel, and Sardonyx
Peridot is the modern August birthstone, a green olivine variety. Some peridot is even found in meteorites. Mohs 6.5 to 7. Hawaiian beaches contain natural green peridot sand from volcanic origins.
Spinel was added as an August birthstone in 2016 and is now one of the most fashionable options. Red spinel has been confused with ruby for centuries; many famous historical rubies in royal collections turned out to be spinel.
Sardonyx is the traditional August birthstone, a banded chalcedony with reddish-brown and white layers. Used in Roman seal rings.
September — Sapphire
The blue variety of corundum, although sapphire actually comes in every color except red (red corundum is ruby). Mohs 9. Sri Lankan, Burmese, and Kashmiri sapphires are the most historically prized.
Padparadscha sapphire, the pink-orange variety, is one of the most beautiful and expensive corundum colors. Star sapphire shows a six-rayed star when cut as a cabochon.
October — Opal and Tourmaline
Opal is the modern October stone. A hydrated silica with the famous play of color called opalescence. Mohs 5.5 to 6.5. Opal requires careful storage because it can crack from temperature changes or low humidity.
Tourmaline is the alternate October stone, a complex borosilicate that comes in nearly every color. Our black tourmaline guide covers the most common form, although October birthday gifts typically use the colored varieties: pink, green, blue, or watermelon (with both pink and green in one crystal).
November — Topaz and Citrine
Topaz is the traditional November stone. A silicate mineral that comes in many colors, but the classic November topaz is the warm imperial topaz, a sherry-yellow to orange variety. Mohs 8.
Citrine is the modern November alternate. The warm yellow quartz. Our citrine guide covers the natural-versus-heat-treated question that matters here. Most commercial citrine is heat-treated amethyst.
December — Tanzanite, Turquoise, and Zircon
Tanzanite was added as a December birthstone in 2002. A blue-violet variety of zoisite, found only in a small area of Tanzania. The deposit is expected to be exhausted within a few generations, which makes tanzanite increasingly valuable.
Turquoise is the traditional December stone. A copper aluminum phosphate, often porous and treated. Used by Indigenous American cultures for thousands of years.
Zircon is the third December option. A natural mineral that has been used as a diamond substitute for centuries because of its high refractive index. Not to be confused with cubic zirconia, which is synthetic and different.
How to buy a birthstone as a gift
A few practical thoughts.
- Pick the month, then pick within the month's options. June, August, October, November, and December all have multiple choices.
- Consider hardness for daily wear. Pearl, opal, and turquoise need more care than ruby, sapphire, or topaz.
- Treatments are common and not a problem if disclosed. Heat treatment of aquamarine, oil treatment of emerald, and stabilization of turquoise are all standard practice.
- Affordable alternatives exist for almost every month. Tumbled stones cost a few dollars. Faceted gems in jewelry cost more.
- Tumbled stones for a personal collection differ from faceted gems for fine jewelry. Both are valid gifts at different price points.
Come visit
If you are in Grass Valley and shopping for a birthstone gift, we are happy to help. The shop is at 139 Mill Street.
Quick FAQ
Why do some months have multiple birthstones?
Birthstone traditions vary across cultures and centuries. The modern list includes alternates for affordability and variety.
Which is the most expensive birthstone month?
April (diamond) is typically the most expensive. May (emerald) and July (ruby) are also costly.
Which is the most affordable birthstone month?
February (amethyst) is among the most affordable. November (citrine), August (peridot), and June (moonstone) are also accessible.
Are lab-created birthstones acceptable?
Yes. Lab-created stones are real chemically. They are usually disclosed as such and cost significantly less than mined equivalents.