Still on my Illustrator practice/training, I found a very useful tutorial by Nathaniel Dodson@tutvid.com. He seems to be very good at what he does and I like the way he teaches and speaks. Ths tutorial is about designing a gemstone or polyhedron using a plethora of Illustrator functionalities and effects. I changed my results a bit and created a Polyhedron which is also a Matryoshka of sorts: one inside the other. It was great fun and extremely useful, and since the tutorial is a bit long, great for practicing. I have added some different colour and shape variations to my resulting artboards, which are included here. Starting with my resulting figure and basic shape.
(Original tut is... http://tutvid.com/adobe-illustrator-tutorials/create-polygon-geometric-gemstone-illustrator-cc/)