Picasso jasper is grey stone with black and brown lines running through it. They sweep and branch across the face like ink strokes, sometimes fine and wiry, sometimes broad and heavy, and they never repeat from one piece to the next. One look at a cut face and the name explains itself.

It is also, strictly, not a jasper. The material is a marble, which means it is calcium carbonate rather than quartz, and it comes out of Utah in the United States. The veining is the fossil record of older limestone that was pressed and heated until the mineral structure reorganised, and the dark lines are the impurities left behind in seams and cracks during that process. Sellers call it Picasso stone and Picasso marble for the same reason they call it jasper. None of the three names is a mineral name, and the one that stuck is the one that sells.

The practical consequence is hardness. True jasper is quartz and sits at six and a half to seven. Calcite sits around three to four, so this is roughly half as hard, and a fingernail will mark it in the wrong place. It does mean the carved pieces need different handling from the rest of the shop, and it is the reason a carved Buddha in this material feels heavier and smoother in the hand than a quartz carving of a similar size.

Traditionally associated with

This is another relatively new stone, being discovered in the late 20th Century. It tends to be kept on a desk, a shelf or an altar, and it is grouped with the other stones used for space clearing.

How I'd keep it

Keep it away from acids and most household cleaners, because acid dissolves calcite and will etch a dull patch into a polished face that cannot be polished back. Warm water and a soft cloth are enough, and dry it rather than leaving it damp. Do not leave it in direct sun for long spells, as calcite can discolour in strong light. The fine lines want a dry soft brush rather than a cloth that will press grit into them.

What to watch for

Check what you are being sold. Picasso jasper, Picasso stone and Picasso marble are the same thing under three names. Separately, dendritic jasper looks similar at a glance and is a different and much harder stone, and dyed grey material is common. The tell for the real thing is the lines themselves. They branch and taper and follow the structure of the stone, so a pattern that sits flat on the surface with no depth to it is usually not the real material.

In the shop

The Carved Laughing Buddha is available in Picasso Jasper for £15, and each carving is cut from one piece, so the veining runs differently on every one.

Free UK shipping on orders over £50. Everything is sent from Luton, and collection is available if you're local.