April has diamond on both lists, and the traditional United Kingdom list adds rock crystal, which is clear quartz.
The two lists for April
Modern list (American Gem Society): Diamond
Traditional list (United Kingdom, National Association of Goldsmiths, 1937): Diamond, Rock crystal
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
Diamond
Diamond is a crystal of carbon, formed deep in the Earth, and the hardest natural material at 10 on the Mohs scale. The name comes from the Greek adamas, “unconquerable”. Diamonds are found in southern Africa, Russia, Canada and Australia, and India was the world’s early source. The trade has a history of conflict diamonds, which led to the Kimberley Process certification scheme. Laboratory-grown diamonds are chemically identical to mined ones, so ask a seller which you are buying.
Rock crystal
Rock crystal is clear, colourless quartz, carved into objects and beads since antiquity. It is hardness 7, affordable and widespread, and it is the stone in our clear quartz guide.
How the idea developed
April is where the gap between lists is easiest to see. The United Kingdom list of 1937, published by the National Association of Goldsmiths, kept an older companion stone for some months, rock crystal for April among them, while the modern American list kept a single headline gem. It is a reminder that birthstone lists were made by the jewellery trade as well as by tradition.
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 rock crystal the same as a diamond?
No. Rock crystal is quartz, hardness 7, and diamond is carbon, hardness 10. They look alike when clear, but they are completely different minerals.
↳ Is a lab-grown diamond a real diamond?
It is chemically and physically the same material, grown in a laboratory. Sellers should tell you which you are buying.