TL;DR: Birthstones are a Western custom that did not arise from ancient astrology but formed in layers: a biblical foundation in the 12 stones of the high priest's breastplate, traditions of protective stones by month and by zodiac sign, then standardisation into a commercial list in the early 20th century. The current list is not a single unchanging table: each tradition and each gem organisation issues a different one, and this article presents those variants instead of choosing one as the standard.
What is a birthstone, and how is the question of its origin posed?
A birthstone (đá tháng sinh in Vietnamese) is the custom of tying each month of the year to one or several gemstones, and the belief that a person born in that month carries that stone as a protective or commemorative object. What is worth noting is that this custom does not come from a single astrological system, nor is there any ancient text that fixes a table of stones for the 12 months. It is the result of layers from several different traditions, and the books of George Frederick Kunz are a relatively systematic English-language record of it[1][2].
Two things that are often merged into one need to be kept apart: birthstones by calendar month, and zodiacal stones tied to the 12 signs. They share roots but developed along different paths, and the tables of the two systems do not coincide. This article follows the convention of presenting both systems side by side, notes where the sources disagree, and does not affirm any healing or fortune-changing effect of stones.
Where do the 12 stones on the high priest's breastplate come from?
Kunz devotes many pages in The Curious Lore of Precious Stones to comparing translations and identifications of these 12 stones, and he notes that scholars themselves argued for centuries over which mineral each name in the ancient text corresponds to[1].
The point to state clearly: this is a tradition of attribution, not a proven historical event. There is no evidence that the ancient Jews used those 12 stones as birthstones. The link between the breastplate and birthstones was established retroactively by later authors. Modern research on the history of jewellery does not treat the current birthstone table as a direct descendant of the breastplate, but as a late association legitimised by the authority of the Bible.
How are stones of the planets and the zodiac signs assigned?
The second layer is Greek and Roman astrology, where each planet was assigned a stone, and each zodiac sign was then assigned a stone through its ruling planet. This assignment has a clear mechanism: whichever planet rules a sign, that planet's stone is the sign's stone. For example, Taurus is ruled by Venus, so stones associated with Venus, such as emerald, are assigned to Taurus; Leo is ruled by the Sun, so it is tied to yellow stones or ruby; Virgo is ruled by Mercury, so it is tied to blue stones or veined stones.
Kunz surveyed beliefs around precious stones in many cultures, including stones by zodiac sign and planet[1][2]. He also notes that some medieval authors held that gemstones are born under the influence of the stars, so each stone carries the nature of the planet that gave birth to it. This is how astrology understands it, not a scientific conclusion: no study has shown that stones are influenced by planets, and Kunz himself, though he recorded a great many legends, did not assert that it was true.
When did the modern birthstone list come about?
This is the part that can be answered fairly clearly. The birthstone table popular today is not an ancient heritage but a product of the jewellery trade of the early 20th century. Kunz reports that he compiled a small booklet titled Natal Stones, Sentiments and Superstitions Associated with Precious Stones, which by 1913 had been printed 21 times[1]. He says that in compiling it he examined nearly all the principal gem collections in the United States, Europe, Mexico, Canada and Asiatic Russia[1].
The current birthstone table is the result of revisions over time, and further tables have been issued by various organisations; no body with scientific or religious authority has issued a birthstone table, since this is a commercial and cultural convention, and so the tables differ in some months. This table was later revised several times, and there are now additional tables from the American Gem Society and other organisations. To state it clearly: no body with scientific or religious authority has issued a birthstone table; this is a commercial and cultural convention, and so the tables differ in some months.
How do birthstone variants differ?
The table below sets side by side two lists that Kunz (1913) records: the list adopted by the National Association of Jewelers in Kansas City in August 1912, and the stones that appear most often across the eight older lists he compared; the number in brackets is how many lists include that stone, alternates included[1].
| Month | Kansas City list, 1912 (main stone; alternate) | Most frequent stone in the eight older lists |
|---|---|---|
| 1 | Garnet | Garnet (7) |
| 2 | Amethyst | Amethyst (8) |
| 3 | Bloodstone; alternate: aquamarine | Jasper (5), bloodstone (4) |
| 4 | Diamond | Sapphire (7), diamond (2) |
| 5 | Emerald | Agate (5), emerald (4) |
| 6 | Pearl; alternate: moonstone | Emerald (4), agate (4) |
| 7 | Ruby | Onyx (5) |
| 8 | Sardonyx; alternate: peridot | Carnelian (5), sardonyx (3) |
| 9 | Sapphire | Chrysolite (6), sardonyx (2) |
| 10 | Opal; alternate: tourmaline | Beryl (8), aquamarine (5) |
| 11 | Topaz | Topaz (8) |
| 12 | Turquoise; alternate: lapis lazuli | Ruby (6), turquoise (2) |
The two columns differ in many months. Kunz notes that the 1912 list moved the ruby from December to July and put the turquoise in December; he also holds that the diamond appears in no birthstone list before the 19th century[1].
Why is each month tied to a kind of stone?
There are three main reasons, and all three are notions, not verified mechanisms.
- Colour and season associations: the sea-blue stone of March is tied to spring, the blue stone of December to winter. Assignment by colour is a later layer, common in 20th-century tables.
- Inheritance from astrology: each month contains one or two signs, and the sign's stone is transferred to the month. This is the older layer, but the ancient astrologers themselves did not agree.
- Commercial factors: when the table was standardised, some stones were chosen because they were easier to sell and easier to source rather than for symbolic reasons. For example, adding aquamarine and tourmaline to the modern table widened the choice for buyers.
Kunz, in The Magic of Jewels and Charms, gives most of his space to amulets and stone talismans in the legends of various peoples, and his manner of presentation is to relate beliefs, not to affirm their efficacy[2]. He tells many stories of stones said to heal, ward off evil or foretell, but always places them in the frame of what people once believed. This is the right way to read those books: as cultural material, not as medical guidance.
How do birthstones and zodiac stones differ?
The two systems differ in three points. First, birthstones follow the calendar month and are fixed by date of birth; zodiac stones follow the sign, and a sign runs across two months, so a person born at the end of March may be Pisces or Aries, with different suggested stones depending on the system. Second, the number of stones differs in each system: 12 months but 12 signs, while some months have two official stones. Third, birthstones are a modern commercial convention, while zodiac stones are a product of ancient astrology, so the two systems are not equally "ancient".
In practice, many people mix the two systems, and reference pages often merge them into a single table. That is not wrong for convenience, but it obscures the fact that the two systems have different origins and logic.
How should the belief in birthstones be understood correctly, and what are its limits?
Birthstones are a cultural custom, worth studying as a historical and social phenomenon, not a method of healing or changing fortune. There is no scientific evidence that gemstones can heal, change destiny or affect physical health. Claims of the kind "stone X cures illness Y" should be read as legend, and should not replace medical advice.
What is worth keeping is the aesthetic and commemorative value: a stone tied to one's birth month can be a gift with personal meaning, a way to remember a birthday, a subject for exploring the history of jewellery. That value is real, and it does not need belief in miracles to exist.
In summary
Birthstones have no single origin. They are the layered product of the biblical tradition of the 12 stones, ancient astrology assigning stones to planets and signs, and the jewellery trade of the early 20th century, which standardised them into a popular table. So when you look up a birthstone, you should know which table you are following, and should not treat any table as an absolute standard.
