July has ruby on both lists, and the traditional United Kingdom list adds carnelian.
The two lists for July
Modern list (American Gem Society): Ruby
Traditional list (United Kingdom, National Association of Goldsmiths, 1937): Ruby, Carnelian
There is no single official birthstone list, so you are free to choose whichever you prefer. You can check any month with our birthstone finder.
About the stones
Ruby
Ruby is red corundum, coloured by chromium, and the same mineral as sapphire. Its hardness is 9, second only to diamond. The finest rubies have traditionally come from Myanmar, and there are sources in Mozambique, Thailand and Sri Lanka. Heating is common and accepted if disclosed, and some famous red stones in crown jewels, including the Black Prince’s Ruby in the British Imperial State Crown, are actually spinel.
Carnelian
Carnelian is orange-red chalcedony, used for seals and beads since antiquity, with a hardness of 6.5 to 7. The region around Khambhat in Gujarat has made carnelian beads for thousands of years. The full story is in the carnelian guide.
How the idea developed
Ruby and carnelian are both red, but they sit at opposite ends of the market, which is a good example of how the old British list paired a great gem with a humbler stone. Both lists are the work of jewellers as well as traditions, and the United Kingdom list of 1937 was published by the National Association of Goldsmiths.
For the wider history of the idea, see our birthstones overview. The modern list follows the American Gem Society, and the traditional list follows the 1937 United Kingdom list, both summarised in Wikipedia, Birthstone.
A different system
Vedic gemstone (ratna) guidance is a different system from birthstones. It is tied to the nine planets and to a birth chart, not to the calendar month, and it belongs to the Vedic tradition, which is covered on our sister site, Nidarshana Vedh. Nothing on this page is Vedic advice.
A note on health. Crystals are valued for beauty, meaning and ritual. There is no scientific evidence that they treat health conditions. If you are struggling with your health or mood, please speak to a doctor.
Frequently asked questions
↳ Is a ruby the same as a sapphire?
Yes, chemically. Both are corundum. Red corundum is called ruby, and corundum of any other colour is called sapphire.
↳ Is every red gem in a crown a ruby?
No. Several historic stones once called rubies have been shown to be spinel.