Astrologers originally gave each month of the year a ruling planet and zodiacal sign with gemstones linked to each – called the birthstone. When this was first devised each sign of the zodiac filled an exact month ie Capricorn filled January, Aquarius February and so on.
Down the centuries in the course of each celestial mass’s journey around the sun, the planets have crept into different positions, so that now each sign begins earlier than the first day of its original month and ends part way through it e.g. Aries now begins on the 21st March rather than completely filling April.
Each zodiac sign is ruled by one or two planets and has one or more stones linked to it called the birthstone. Birthstones are particularly lucky to the people born under the influence of its planetary ruler, according to many practitioners of astrology, and should be worn or carried on or about the person. This can bring good luck, protection, good health and so on, according to the nature of the stone concerned, to the wearer of the gem.
Below is a chart compiled from the many available and includes only the stones common to the majority of them. It is by no means a complete list, as there are many variations on the charts written throughout the centuries.
| Dates | Sign | Planet | Birthstone |
| Mar 21st – April 21st | Aries | Mars | Diamond |
| Apr 22nd – May 21st | Taurus | Venus | Agate & Emerald |
| May 22nd – Jun 21st | Gemini | Mercury | Pearl & Beryl |
| Jun 22nd – Jul 22nd | Cancer | Moon | Onyx & Ruby |
| Jul 23rd – Aug 23rd | Leo | Sun | Carnelian & Peridot |
| Aug 24th – Sept 23rd | Virgo | Mercury | Sapphire |
| Sept 24th – Oct 23rd | Libra | Venus | Opal & Tourmaline |
| Oct 24th – Nov 22nd | Scorpio | Mars & Pluto | Topaz & Malachite |
| Nov 23rd – Dec 21st | Sagittarius | Jupiter | Turquoise & Lapis Lazuli |
| Dec 22nd – Jan 20th | Capricorn | Saturn | Garnet & Hyacinth |
| Jan 21st – Feb 19th | Aquarius | Uranus & Saturn | Amethyst & Aquamarine |
| Feb 20th – Mar 20th | Pisces | Neptune & Jupiter | Bloodstone & Moonstone |
For example, a person born on June 21st could wear a ruby which seemingly promotes tranquility or an onyx that is said to promote strengthening of the bone marrow. If the zodiacal hieroglyph is also carved into the birthstone it is said to also increase the stones virtue.
