Our smallest agate slices: little pocket-sized windows into a volcanic rock.

Agate forms when silica-rich water seeps into gaps in volcanic rock and builds up, one thin layer at a time. Slice it, polish it, and those layers show up as bands, a bit like tree rings. Every colour except Natural is dyed; the dye soaks into the bands and makes the light glow through. Natural is the agate's own undyed colour.

They're cheap, cheerful and impossible to buy just one of. Kids love holding them up to a window. Crafters scoop up handfuls for art projects, and people who make crystal grids like them as colourful filler.

How to use it

• Hold one up to a sunny window
• Add colour to a crystal grid
• Use them in resin or collage crafts
• Tuck them into party favour bags

Care: Rinse with plain water and dry right away, and keep the dyed ones out of long hours of direct sun so the colour stays bright.

The details

• Stone: Agate
• Unit size: 1 1/2" to 2 1/2"
• Options: Black (Enhanced), Blue (Enhanced), Green (Enhanced), Natural, Pink (Enhanced), Purple (Enhanced), Red (Enhanced), Teal (Enhanced)
• Sold as: Single piece
• Country of origin: Brazil