A pretty pale blue (kind of lavender) chalcedony with a natural botryoidal or bubble surface. This material used for these cabochons comes from Turkey. I took some of the pictures with a flash which seems to brighten the color a little.

Chalcedony (kal SED' nee) is any form of microcrystalline quartz , where the crystals are too small to be seen without high magnification. However, in the rock world, only the translucent or transparent, single color types are sold as "chalcedony". Patterned stones are usually called agates or jaspers.

The name probably comes from Chalcedon or Calchedon, an ancient port city on the Sea of Marmara in modern-day Turkey. Chalcedonies usually have a waxy luster and a hardness of 7. They are tough gems, good for all jewelry and require no special care in wearing or cleaning.