A polished freeform with blue running through the banding, and the blue is not a pigment.
Most agate colour comes from something physically present in the stone. Iron oxides give the reds, oranges and yellows found across the majority of banded agate. Blue and grey in chalcedony usually work differently: there is often nothing blue in there at all. The colour is produced by light scattering off structures far too small to see, the same physics that makes the sky blue rather than transparent.
Which is why this piece will not look the same in two places. Held up to a window it behaves differently to how it sits on a shelf under a lamp. Turn it around before deciding where it lives.
Mineral: Chalcedony (silicon dioxide, SiO₂), banded, so agate
Crystal system: Trigonal
Origin: Madagascar
Hardness: 6.5 to 7 on the Mohs scale; durable, though the polished surface will dull if knocked about
Treatment: None
Dimensions: 9.3 x 5.97 x 9.85 cm
Weight: 805 g
You will receive the exact piece photographed.