Naturally coloured pale blue fluorite crystals from Cave-in-Rock, Illinois. The crystals were cleaved by a miner to this distinctive octahedron form. They are actually clearer than they look in the photos. They are discreetly glued to a silver or gold coloured base so that they stand for display. Being cleaved to their natural planes each one is somewhat irregular but each one has at least one angle that displays nicely as shown. The last photo shows the variety of colours that these crystals occur in. Just put "fluorite" in the search box to find the other options.
Left is just under 1/2 inch (1.3 cm) wide, just under 1/2 inch (1.3 cm) deep and just over 1/2 inch (1.3 cm) tall.