MAY BIRTHSTONE HISTORY: Affordable vs. Most Expensive

May birthstone had beautiful bands, until the green gem from next month took over. The difference could not be more pronounced. The birthstone for May went from a relatively affordable gem to one of the most expensive.


You shall make a breastplate of judgment. … You shall set in it settings of stones in four rows: a row of sard, peridot and emerald shall be the first row … and the third row a ligure, an agate and an amethyst …

— Exodus 28:15-19

Agate is among the gems on Aaron’s breastplate. Known by the name shevo in Hebrew,1 agate is associated with the 3rd sign of the zodiac, Gemini, and the partially concurrent month of May. The Jews, Rome, Italy, Spain and India all honored agate as May birthstone.

The banded form of chalcedony, agate occurs in a wide variety of colors and patterns. Achates in Greek,2 agate was named after the river Achates in Sicily where the banded gem was found.3 One big question concerning this birthstone is, what were the colors of the agate on Aaron’s breastplate?

The agate on the priestly breastpiece must have come from Egypt, whence the Hebrew people fled in the Book of Exodus. Chances are the gemstone came from the variety of agate often found in Egyptian work. The agate on Aaron’s breastplate would indeed have gray and white bands.4

However, the traditional May birthstone is not limited to the gray or white variety of agate. The ancients knew agate to occur in a variety of bands and colors, and referred to any of these stones by the same name.

Still, the agate prescribed by the ancients as May birthstone is most probably white. Though agate is the gem on Aaron’s breastplate, there was no mention of agate among the Foundation Stones of Revelation. Instead of agate, the Foundation Stone corresponding to the month of May is chalcedony. A chalcedony gem can be an entirely white piece of agate.


The foundations of the city’s wall were adorned with all kinds of precious stones. The first foundation was jasper; the second, lapis lazuli; the third, chalcedony …

— Revelation 21:19

It is not just agate, the banded chalcedony, that is the birthstone for May. The mother gem, chalcedony, is also May birthstone from the Bible. While agate is the gem on Aaron’s breastplate, chalcedony by its Greek name chalkedon5 was the Foundation Stone in Revelation. As the 3rd Foundation Stone, chalcedony goes to the 3rd sign of the zodiac, Gemini, and the partially concurrent month of May.

However, the Jews alone kept chalcedony as May birthstone. Most ancient cultures simply had agate for May, while those who honored chalcedony transferred the gem to June. Nevertheless, the fact that the Jews acknowledged chalcedony for May says a great deal about its authenticity as birthstone for May, considering that the gem’s designation comes from the Christian Book of Revelation, which the Jews do not hold with reverence.

Chalcedony must have gotten its name from Turkey’s town of Chalcedon, where the gemstone was found. While known today to comprise a wide variety of translucent to opaque quartz, chalcedony traditionally designated the white gem, though the name also applied to the pale blue variety. The agate on the priestly breastplate, whether in the First or Second Temple of Jerusalem, must have been largely white in color, if not entirely white.


Along with agate and chalcedony, carnelian is birthstone for May in ancient Jewish culture. Though, like agate, carnelian is a variety of chalcedony, the red gem was a rather odd choice of alternate May birthstone for the Jews, who also assigned carnelian to August. Europe in general honored carnelian in August, but not in May.

Carnelian is the red variety of chalcedony.

From Mauro Cateb, CC BY-SA 3.0


Emerald is currently the birthstone for May. Originally June’s gem, emerald became May birthstone by the 1400s. The shift was not sudden. In a few ancient cultures, the birthstones for May and June had been swapped. To accommodate India’s June birthstone, pearl, the Arabs moved the like-colored agate and chalcedony to June, and transferred the native emerald to May. Poland and Russia followed suit. By the 15th century, both emerald and agate were May gemstone in Europe. America’s jewelers upheld emerald’s position in 1912, where they removed agate altogether from the entire list of birthstones.6

The difference in value between agate and emerald may have decided the fate of these neighboring birthstones. The wider availability of the multi-colored agate made the banded gem more affordable, while the extremely rare emerald is among the world’s most expensive jewels. Gem traders make more money selling a single emerald than they would disposing of many an agate. Emerald was by far more important in trade, which has shaped the list of birthstones over the years. Its towering value consequently allowed emerald to replace the less lucrative agate as May birthstone.

Emerald is the green variety of beryl. This gem comes from the same mineral as aquamarine, and is distinguished simply by its color. Emerald represents the color green of the precious stones.

From Ra’ike, CC BY-SA 3.0


Britain added chrysoprase as alternate gem to May’s emerald. Given that the primary birthstone for May is green, the addition of chrysoprase was largely, if not entirely, due to color. Green is the May birthstone color in both the US and Britain. Like emerald, chrysoprase occurs exclusively in green, albeit in a pastel shade.

The green variety of chalcedony, chrysoprase is most popular in apple green.

Botswana Agate Bracelet

Valuable May Birthstone

May is the story of gem neighbors exchanging houses until one finally got evicted. The colorful agate lived a glamorous life as the birthstone of May. However, some cultures thought it better if agate exchanged houses with the rich gem from June. By the 1400s, agate and emerald lived together in May, where they continued to cohabit for 4 centuries. One momentous day, however, the powers that be decided the final fate of the two gems. Less valuable agate had to say goodbye to May never to be enthroned again in any other month.

Know Their Magic

Each birthstone for May is attributed with magical properties. Know the magical powers of May stone, as well as those of your zodiac birthstones, when you read my book Power Birthstone.

Learn the magic of May Birthstone



“Exodus 28.” The Bible. Bible Hub, Accessed 28 July 2019.


“Exodus 28.” Septuagint. Blue Letter Bible, Accessed 28 July 2019.


Theophrastus. On Stones. Trans. Earle R. Caley and John F. C. Richards. Colombus: The Ohio State University, 1956. p. 52.


Kunz, George Frederick. “On the High-priest’s Breastplate.” The Curious Lore of Precious Stones. New York: Halcyon House, 1938. pp. 282-296.


“Revelation 21.” The Bible. Bible Hub, Accessed 28 July 2019.


Knuth, Bruce G. “Birthstones.” Gems in Myth, Legend and Lore. Revised ed. Parachute: Jewelers Press, 2007. pp. 293-327.

Published October 16, 2019