Start with the shell
| Nut | Shell | Shape | Kernel |
|---|---|---|---|
| Walnut | Hard, deeply wrinkled, raised seam | Round to oval | Brain-shaped, deeply grooved |
| Pecan | Thin, smooth, oval, lengthwise seam | Elongated | Smooth, ridged, reddish-brown |
| Almond | Pale, hard, pitted with small holes | Flat and teardrop-shaped | Wrinkled brown skin, creamy inside |
| Hazelnut | Smooth, glossy, round, flat pale scar | Round | Smooth brown skin, pale inside |
| Macadamia | Extremely hard, round, small dimple | Spherical | Creamy white, perfectly round |
| Brazil nut | Thick, rough, ridged, triangular | Triangular in cross-section | Large, smooth, cream with a brown patch |
| Cashew | Toxic shell, always sold shelled | Curved, kidney-shaped | Pale cream, smooth |
| Pistachio | Thin, pale, splits open naturally | Small oval | Green with a purple-brown skin |
| Peanut | Papery, ridged, in a pod of two | Oval with a central seam | Two halves, papery skin |
| Chestnut | Glossy brown with a pale base scar | Rounded with a pointed tuft | Pale, starchy, edible only cooked |
Shelled kernels: the harder job
- Shape first. Teardrop with a wrinkled skin is an almond. Kidney-curved and pale is a cashew. Perfectly round and creamy is a macadamia.
- Colour next. Green kernels with a split shell are pistachios. Brazil nuts are large and smooth with a distinctive brown patch on the surface.
- Skin texture is useful. Almonds have a finely wrinkled brown skin that slips off. Hazelnuts have a smooth brown skin that clings.
- A visible central seam and a papery red-brown skin means peanut, which is a legume rather than a true nut.
- Size alone separates macadamia and brazil nut from everything else in a mixed bag.
Chestnut or conker?
This is the one nut confusion that can make you ill. Sweet chestnut and horse chestnut look superficially similar, but horse chestnut, the conker, is toxic and should never be eaten.
A sweet chestnut has a pointed tuft at the tip and at least one flat side, because the nuts grow packed together in the spiny case. The base scar is small and irregular. A horse chestnut is smooth, round, glossy and mahogany-brown with a large, pale, circular scar where it joined the case.
Sweet chestnut cases are densely spiny, like a sea urchin. Horse chestnut cases are thick and leathery with only a few short spines.
Allergy warning
Tree nuts and peanuts are among the most common causes of severe food allergy, and reactions can be triggered by very small amounts. Peanut is a legume rather than a tree nut, but it causes the same kind of reaction and is often managed together.
No photo can tell you whether a nut is safe for a particular person, and no identification tool can. If you have a nut allergy, or you are cooking for someone who does, treat any unidentified nut as a risk and check the packaging.
Roasted, salted and processed
Processing changes appearance. Roasted nuts are darker and their skins loosen. Salted nuts carry visible salt crystals. Honey-roasted and coated nuts lose most of their identifying surface detail.
If you are identifying from a mixed snack bag, the shape of the kernel is your best guide, followed by size. The shells will not be there to help.
Identifying a nut is easy in the shell and much harder once it has been shelled, roasted and salted. The shell carries most of the information, so if you have a choice, photograph the nut before you crack it.
This guide covers the nuts you are most likely to meet in a mixed bag, a baking cupboard or a garden, and the one confusion that genuinely matters for safety.
Frequently Asked Questions
By the shell. Walnuts are deeply wrinkled with a raised seam, pecans are smooth and thin with a lengthwise seam, hazelnuts are smooth and round with a flat pale scar, and macadamias are perfectly round and extremely hard.