October has two birthstones, opal and tourmaline. Compare colour, durability and care, and learn to spot opal doublets, triplets and lab-grown opal before you buy.
March has two birthstones, aquamarine and bloodstone. Learn how aquamarine colour is judged, why most is heated, and how to tell it from blue topaz.
The February birthstone is amethyst. Learn how its colour is judged, what Siberian and Rose de France mean, why some fades, and how to buy one wisely.
August has three birthstones: peridot, spinel and sardonyx. Compare their colour, durability and price, and learn which suits a daily ring or a gift.