Back in stock! 
These are now priced at £24.95 I have Amethyst, Rose Quartz and Chevron Amethyst. 
This six piece set contains the five elemental Platonic Solids, plus the Sphere. 
Each of the platonic shapes has different length sides but as a generalisation each shape has sides of in between 1-2 cms long. You can get a fairly good idea of size by looking at the photo with the hand.

A platonic solid is a three-dimensional shape whose faces are all congruent regular polygons (two-dimensional shapes bounded by straight line segments) where the same number of faces meet at every angle. The Greeks are believed to have been the first to discover that there are only five platonic solids. These are:
Tetrahedron (three triangles meet at each vertex)
Octahedron (four triangles meet at each vertex)
Icosahedron (five triangles meet at each vertex)
Hexahedron or Cube (three squares meet at each vertex)
Dodecahedron (three pentagons meet at each vertex)
In his work Plato linked the five platonic solids to the elements. Tetrahedron represents fire (also spirit), the cube earth, the octahedron is air (also can be seen as mental planes), icosahedron represents water (emotions) and the dodecahedron represents the constellations and heavens (universe). As a group the platonic solids are in balance and can be used in healing or simply in your home or place of work to give focus to the idea of bringing the four elements and the fifth universal element (some may call God) into balance within you.

Gemstone Geometric Platonic set